Ibn Majah

Benefit:
Regarding the aforementioned narration, Hafiz Ibn Abd al-Barr rahimahullah writes:
There is a difference of opinion concerning the final words of this hadith.
In some versions, the wording is "fa la shay'a 'alayh" (then there is nothing upon him), in some "fa la shay'a lahu" (then there is nothing for him), in some "fa laysa lahu shay'un" (then he has nothing), and in some "laysa lahu ajr" (he has no reward).
Regarding these wordings, Imam Ibn al-Qayyim rahimahullah, Hafiz Ibn Abd al-Barr, Shaykh al-Albani, and the researchers of al-Mawsu'ah al-Hadithiyyah write:
That among these, the most authentic wording is "fa la shay'a 'alayh".
Shaykh al-Albani rahimahullah has explained its meaning as follows:
That he will not receive a specific reward.
He will only receive the reward of the funeral prayer (salat al-janazah).
Absolute negation of reward cannot be established,
because it is proven from an authentic hadith that the Messenger of Allah sallallahu alayhi wa sallam himself performed the funeral prayer in the mosque.
Furthermore, when Imam Ahmad ibn Hanbal rahimahullah was asked about performing the funeral prayer in the mosque, he replied:
This is Sunnah.
Also, Umar radi Allahu anhu led the funeral prayer of Abu Bakr radi Allahu anhu in the mosque.
Similarly, Suhayb radi Allahu anhu led the funeral prayer of Umar radi Allahu anhu in the mosque itself, in the presence of the senior Companions, and no one objected.
Therefore, it cannot be said that performing the funeral prayer in the mosque is impermissible; however, performing it outside the mosque is more virtuous and better.

Benefits and Issues:
Shaykh al-Albani has also declared the wording "falahu shay’un lahu" to be correct instead of "falahu shay’un ‘alayhi."
Its translation would be that the one who performs the funeral prayer (salat al-janazah) in the mosque will not receive anything.
And its meaning has been explained as: he will not receive the special reward.
He will receive only the reward of the funeral prayer (salat al-janazah).
The absolute negation of reward cannot be established for this reason:
That it is proven by an authentic hadith that the Messenger of Allah (sallallahu alayhi wa sallam) himself performed the funeral prayer (salat al-janazah) in the mosque.
Therefore, performing the funeral prayer (salat al-janazah) in the mosque cannot be declared impermissible.
However, performing it outside the mosque will be considered superior.
And Allah knows best.
(For further details, see:
al-Sahihah: 5/462, Hadith 2351)