At what point should one stand up when hearing the iqaamah?

Praise
be to Allah.

Firstly:

The scholars (may Allah have mercy on
them) differed concerning the point at which one should stand up to pray. There
are several opinions that were mentioned by an-Nawawi
in al-Majmoo‘ (3/233), and
they are as follows:

(i)               
That he should stand up when the
muezzin starts to recite the iqaamah. This is the
view of ‘Ata’ and az-Zuhri

(ii)             
That he should stand up when the
muezzin says “hayya ‘ala as-salaah (come to prayer)”. This is the view of Abu Haneefah.

(iii)           
That he should stand up when the
muezzin has completed the iqaamah. This is the view
of ash-Shaafa‘i.

(iv)           
That there is no specific point
at which one should stand up; rather it is permissible for the worshipper to
stand up at the beginning of the iqaamah, during it
or at the end of it. This is the view of the Maalikis.

(v)             
That it is Sunnah
to stand up when the muezzin says “Qad qaamat is-salaah (prayer is
about to begin)” if the worshipper can see the imam; if he cannot see him, then
he should stand up when he does see the imam. This is the view of Imam Ahmad.

There is no clear evidence from the Sunnah to support any of these opinions; rather this is the
ijtihaad worked out by the imams according to what
each of them thought was correct.

Based on that, the matter is broad in
scope, so the worshipper may stand up whenever he wants, at the beginning of
the iqaamah or during it. But the Sunnah
indicates that if the muezzin gives the iqaamah for
prayer when the imam has not yet entered the mosque, then the worshippers may
not stand up until they see him.

It was narrated that Abu Qataadah (may Allah be pleased with him) said: The
Messenger of Allah (blessings and peace of Allah be upon him) said: “When the iqaamah for prayer is given, do not stand up until you see
me.”. Narrated by al-Bukhaari (637) and Muslim (604). According to a version narrated by Muslim: “Until you see that I have come out.”