What are the best fields of worldly work, employment or trade?

Shaykh al-Islam Ibn Taymiyah was asked the following
question: 

I ask the shaykh and imaam, the follower of the salaf
(earlier generations) and the leader of the later generations, the most
knowledgeable man whom I have met in the east or the west, Taqiy al-Deen
Abu’l-Abbaas Ahmad Ibn Taymiyah, to explain to me the best means of
earning a living. 

He (may Allaah have mercy on him) answered as follows: 

The best way of earning a living is to put one’s trust
in Allaah and have faith that He is Able to take care of you, and to
think well of Him. That means that one who is keen to earn a living
should turn to Him and call upon Him, as Allaah said, according to the
report (hadeeth qudsi) in which His Prophet

(peace and blessings of Allaah be upon him) said: “ ‘All of you are
hungry except those whom I feed; ask Me for food and I will feed you.
All of you are naked except those whom I clothe. Ask Me to clothe you
and I will clothe you.’” And al-Tirmidhi narrated from Anas (may Allaah
be pleased with him) that the Messenger of Allaah

(peace and blessings of Allaah be upon him) said: “Let each one of you
ask his Lord for whatever he needs, even if it is a thong for his sandal
when it breaks, for if Allaah does not make it easy for him, he will
not be able to fix it.” (A similar reports from Umm al-Mu’mineen ‘Aa’ishah
(may Allaah be pleased with her) has been classed as saheeh. See al-Silsilah
al-Da’eefah, no. 1362). 

Allaah says in His Book (interpretation of the meaning): 

“… and ask Allaah of His Bounty”

[al-Nisa’ 4:32 – check this is the right quote] 

“Then when the (Jumu‘ah) Saaaht (prayer) is ended,
you may disperse through the land, and seek the Bounty of Allaah (by
working)…”[al-Jumu’ah 62:10] 

Although this refers to Jumu’ah (Friday prayers), the meaning applies
to all the prayers. 

Hence – and Allaah knows best – the Prophet

(peace and blessings of Allaah be upon him) told us to say when entering
the mosque, “Allaahumma iftah li abwaab rahmatika (O Allaah,
open to me the gates of Your mercy),” and when leaving the mosque to
say, “Allaahumma inni as’aluka min fadlika (O Allaah, I ask You
of Your Bounty).” And Ibraaheem the close friend of Allaah (peace be
upon him) said:  

“so seek your provision from Allaah (Alone), and worship
Him (Alone), and be grateful to Him”

[al-‘Ankaboot 29:17 – interpretation of the meaning] 

This is a command, and a command demands a response. So seeking the
help of Allaah, turning to Him with regard to the matter of provision
and other matters, is an important principle. 

Then one should seek to earn money with self-respect
and pride, so that Allaah may bless it for him; one should not take
it with an attitude of desperation and greed. Rather money should be
like the toilet, which one needs but which does not hold any special
place in one’s heart. Striving to earn money should be like striving
to fix the toilet. According to a marfoo’ hadeeth which was narrated
by al-Tirmidhi and others, “Whoever wakes up and this world is his main
concern, Allaah will make him scattered and shattered, and he will feel
a sense of panic and loss, and he will get nothing of this world except
that which was already decreed for him. But whoever gets up and is mostly
concerned about the Hereafter, Allaah will cause him to feel focused
and content, and will give him a feeling of being independent, and worldly
gains will come to him willingly or unwillingly.” 

One of the salaf said: You are in need of this world
but you are in greater need of your share of the Hereafter. If you start
with your share of the Hereafter, then your share of this world will
automatically come with it. Allaah says (interpretation of the meaning): 

“And I (Allaah) created not the jinn and mankind except
that they should worship Me (Alone).

I seek not any provision from them (i.e. provision
for themselves or for My creatures) nor do I ask that they should feed
Me (i.e. feed themselves or My creatures).

Verily, Allaah is the All-Provider, Owner of
Power, the Most Strong” [al-Dhaariyaat 51:56-58] 

With regard to specifying a particular means of earning
a living, whether it be in industry, business, construction, farming,
etc., this varies from one person to another. I do not know of any general
ruling, but if there is a direction that a person wants to take, then
let him seek the guidance of Allaah and pray istikhaarah as taught by
the teacher of all good

(peace and blessings of Allaah be upon him), for there is such great
blessing in that that it cannot be comprehended, then whatever is made
easy for him, he should be content with that, unless it is something
which is objectionable on Islamic grounds.