Sunan Abu Dawud
606
Sahih+3

Jabir said :when the prophet (ﷺ) became seriously ill, we prayed behind him while he was sitting and Abu Bakr was calling “Allah is most great “ to cause the people to hear the TAKBIR. Then he (the narrators) narrated the rest of the tradition

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid