If someone never fasted Ramadan in his life because of his sickness, will he be deprived from entering Paradise through the gate of ar-Rayyaan?

Praise
be to Allah

Firstly: 

If a person wants to do good, with a firm and sincere
intention, but he is prevented from doing it by an excuse such as sickness,
incapacity, or some other legitimate excuse, he will be of the same status
as the one who does it. 

Al-Bukhaari (4423) narrated from Anas ibn Maalik (may Allah
have mercy on him) that the Messenger of Allah (blessings and peace of Allah
be upon him) came back from the campaign to Tabook and when he drew near to
Madinah, he said: ““In Madinah there are people who, whenever you travelled
any distance or crossed any valley, were with you.” They said: O Messenger
of Allah, even though they are in Madinah. He said: “Even though they are in
Madinah, because they were kept there by excuses.” 

Ibn Maajah (1344) narrated from Abu’d-Darda’ that the Prophet
(blessings and peace of Allah be upon him) said: “Whoever goes to bed
intending to wake up and pray during the night, but is overwhelmed by sleep
until morning comes, what he intended will be recorded for him, and his
sleep is a charity given to him by his Lord.”

Classed as saheeh by al-Albaani in Saheeh Ibn Maajah. 

It was narrated and classed as saheeh by at-Tirmidhi (2325),
and also narrated by Ahmad (18031) from Abu Kabshah al-Annamaari that he
heard the Messenger of Allah (blessings and peace of Allah be upon him) say:
“In this world there are four types of people: a person upon whom Allah
bestows wealth and knowledge, so he fears his Lord with regard to it,
upholds ties of kinship with it, and acknowledges the rights of Allah
concerning it – he will have the highest status; a person upon whom Allah
bestows knowledge but does not grant him wealth, so he is sincere in his
intention and says: ‘If I had wealth, I would do the same as So and so’ – so
he will be rewarded according to his intention and the reward of both will
be the same; a person upon whom Allah bestows wealth but does not grant him
knowledge, so he squanders his wealth without knowledge, and does not fear
his Lord with regard to it or uphold his ties of kinship with it, and he
does not acknowledge the rights of Allah concerning it – he will be the
lowest in status; and a person upon whom Allah has not bestowed wealth or
knowledge, so he says: ‘If I had wealth, I would do the same as So and so’ –
so he will be judged according to his intention, and the burden of sin of
both will be the same.” 

Classed as saheeh by al-Albaani in
Saheeh Sunan at-Tirmidhi 

Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him)
said: 

Whoever intends to do a righteous deed and does as much of it
as he is able to, but is unable to complete it, will have the same reward as
one who does it. 

End quote from Majmoo‘ al-Fataawa (22/243) 

He also said: 

These people intended to do the deeds that they used to do,
and wanted to do that, but they were unable to do it, so they will be of the
same status as those who did it. 

End quote from Mamoo‘ al-Fataawa (10/441) 

He also said: The one who genuinely wants to do it, and also
does as much as he is able to, will be of the same status as the one who did
it in full. End quote from Majmoo‘ al-Fataawa (10/731) 

This sharing or equality between the one who intends to do it
and the one who does it, that is mentioned in the text, only refers to the
basic reward for the deed; that does not imply that he will have the same
reward as the one who does it in all aspects. 

Ibn Rajab (may Allah have mercy on him) said: 

The words “the reward of both will be the same” are
understood to mean that they will be the same with regard to the basic
reward for that deed, but not in terms of the multiple reward, because
multiplication of the reward is only for the one who actually did it, not
for the one who intended to do it but did not do it.

End quote from Jaami‘ al-‘Uloom wa’l-Hikam (2/321) 

Muslim (1909) narrated from the hadith of Sahl ibn Hunayf
(may Allah be pleased with him) that the Prophet (blessings and peace of
Allah be upon him) said:
“Whoever sincerely asks Allah for martyrdom, Allah will cause him to attain
the status of the martyrs, even if he dies in his bed.” 

It says in ‘Awn al-Ma‘bood (4/268): 

“Allah will
cause him to attain the status of the martyrs”
as a reward to him for his sincerity in seeking martyrdom, “even
if he dies in his bed”,
because each of them (the one who died as a martyr and the one who died in
his bed) intended good and did what they were able to do, so they will be
equal in terms of the basic reward. End quote. 

Al-Mannaawi (may Allah have mercy on him) said: 

“even if he dies in his bed” because each of them intended
good and did what he was able to, so they will both be equal in terms of the
basic reward, but the fact that they will be equal in this regard does not
necessarily mean that they will be equal in the way they are rewarded or in
the details of their reward, because the reward for a deed and the intention
(that precedes it) is greater than the reward for the intention alone. If a
person intends to perform Hajj but does not have any wealth with which to do
so, he will be rewarded (for his intention) but his reward will be less than
that of the one who actually does Hajj. Undoubtedly what the one who is
killed attains of the reward of martyrdom will be greater than the reward of
the one who intends it but dies in his bed, even if he will still attain the
status of martyr. Although they are equal in reward, the deeds of the one
who actually does it dictate that he should be given an extra reward and
brought closer to Allah. This is the bounty of Allah that He bestows upon
whomever He will. 

End quote from Fayd al-Qadeer (6/186) 

Secondly: 

Al-Bukhaari (1896) and Muslim (1152) narrated that Sahl ibn
Sa‘d (may Allah be pleased with him) said: The Messenger of Allah (blessings
and peace of Allah be upon him) said: “In Paradise there is a gate called
al-Rayyaan, through which those who fast will enter on the Day of
Resurrection, and no one else but them will enter it. It will be said: Where
are those who used to fast? And they will enter through it. When the last of
them has entered, it will be shut and no one else will enter through it.” 

So the gate of ar-Rayyaan is only for those who fast, because
they bore with patience thirst during the day in Ramadan, especially during
the hot summer days. 

Ibn al-Jawzi (may Allah have mercy on him) said: 

With regard to the gate of fasting being called the gate of
ar-Rayyaan, this is entirely appropriate, because the reward for the fasting
person who becomes thirsty is to be given water (yurwa), hence it is
called by the name of the reward.

End quote from Kashf al-Mushkil (3/391) 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

“Ar-Rayyaan” means the one who is given water (yurwa),
because those who fast become thirsty, especially during the long hot summer
days. So they will be rewarded by this gate being named for that which is
applicable specifically to them: the gate of ar-Rayyaan. 

End quote from Sharh Riyadh as-Saaliheen (5/271) 

If a person is suffering chronic sickness which makes him
unable to fast, so he feeds the poor in lieu of fasting, and Allah knows
that if he was able to do so, he would fast, then he will have the basic
reward of one who fasts, without that reward being multiplied and without
the virtue that results from fasting. 

What appears to be the case is that the promise mentioned in
the hadith, of being admitted to Paradise through the gate of ar-Rayyaan, is
part of the extra reward that is only for the one who fasts, and it is extra
to the basic reward. That is only for those who fast in a real sense, not
those who intend to fast but are unable to do so. 

In fact it is more likely that this particular virtue is not
for everyone who fasts; rather it is for those who focus on fasting to the
extent that they observe a lot of supererogatory fasts, not just the
obligatory fast. 

Az-Zarqaani said in his commentary on al-Muwatta’
(3/77):

“And I hope that you will be one of them” – the scholars
said: Hope on the part of Allah or His Prophet means that that thing will
definitely happen. This was stated clearly in the hadith of Ibn ‘Abbaas that
was narrated by Ibn Hibbaan, in which it says: He said: “Yes, and that is
you, O Abu Bakr.” In this hadith there is an indication of how few those
people will be who will be called from all of those gates, and there is also
an indication that what is meant is voluntary deeds of the types mentioned,
not the obligatory deeds, because there are many who do all kinds of
obligatory deeds, in contrast to voluntary deeds, for there are very few who
do all kinds of voluntary deeds. End quote. 

Ibn ‘Abd al-Barr said:

This indicates that not all people are enabled by Allah to do
all types of righteous deeds, and that some may be enabled by Allah to do
some deeds but be deprived of doing others, and only a few people will be
enabled by Allah to do all types of righteous deeds, and Abu Bakr as-Siddeeq
(may Allah be pleased with him) was one of those few.

End at-Tamheed (7/185) 

The fact that the one who was excused from fasting will not
enter Paradise through that gate will not matter, if he fears Allah and does
good deeds, for Paradise has many gates, as Allah, may He be exalted, says
(interpretation of the meaning):

“ ‘Adn (Eden)
Paradise (everlasting Gardens), which they shall enter and (also) those who
acted righteously from among their fathers, and their wives, and their
offspring. And angels shall enter unto them from every gate”

[ar-Ra‘d 13:23]. 

Al-Bukhaari (1897) and Muslim (2027) narrated from Abu
Hurayrah (may Allah be pleased with him) that the Messenger of Allah
(blessings and peace of Allah be upon him) said: “Whoever gives a pair of
anything for the sake of Allah will be called from the gates of Paradise: ‘O
slave of Allah, this is good.’  Whoever was one of the people of prayer will
be called from the gate of prayer; whoever was one of the people of jihad,
will be called from the gate of jihad; whoever was one of the people of
fasting, will be called from the gate of ar-Rayyaan; and whoever was one of
the people of charity will be called from the gate of charity.” 

Whoever misses out on the virtue of one kind of righteous
deed because he has an excuse has many other righteous deeds that he may do.
So whoever misses out on the gate of ar-Rayyaan, let him strive to be among
the people of the other gates, such as the gate of prayer, the gate of
jihad, the gate of Hajj, the gate of charity, or other gates of Paradise. 

Please see also the answer to question no.
148176. 

And Allah knows best.