Ruling on offering the funeral prayer in the mosque

The Sunnah is to offer the funeral prayer in a place that is
just for funerals, outside the mosque, because of the report in al-Bukhaari
(1245) from Abu Hurayrah (may Allaah be pleased with him) which says that
the Messenger of Allaah (peace and blessings of Allaah be upon him)
announced the death of the Negus on the day on which he died, then he went
out to the prayer-place and lined them up in rows, and said takbeer four
times. 

But if the funeral prayer is offered in the mosque, there is
nothing wrong with it, because of the report narrated by Muslim (973) which
says that ‘Aa’ishah (may Allaah be pleased with her) issued orders that the
bier of Sa’d ibn Abi Waqqaas be brought into the mosque and the funeral
prayer be offered for him. The people objected to that, but she said: How
quickly the people forget! The Prophet (peace and blessings of Allaah
be upon him) did not offer the funeral prayer for Suhayl ibn al-Bayda’
except in the mosque. 

Ibn Qudaamah (may Allaah be pleased with him)said in
al-Mughni (2/186): There is nothing wrong with offering the funeral
prayer for the deceased in the mosque if there is no fear that it may become
contaminated. This is the view of al-Shaafa’i, Ishaaq, Abu Thawr and Dawood.
End quote. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was
asked: What is the correct opinion on the ruling on offering the funeral
prayer for the deceased in the mosque? 

He replied: The correct view is that there is nothing wrong
with offering the prayer for the deceased in the mosque, because the Prophet
(peace and blessings of Allaah be upon him) offered the funeral prayer
for Sahl ibn Bayda’ in the mosque. End quote. 

Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen
(17/160). 

And Allaah knows best.