ENOfficial
‘Abd ar-Rahman b. Abu Laila said that Zaid b. Arqam used to say “God is most great” four times over their dead at funerals, but once he said it five times. On being questioned about it he replied that God's messenger used to do so. Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي لَيْلَى قَالَ: كَانَ زَيْدُ بْنُ أَرْقَمَ يُكَبِّرُ عَلَى جَنَائِزِنَا أَرْبَعًا وَأَنَّهُ كَبَّرَ عَلَى جَنَازَةٍ خَمْسًا فَسَأَلْنَاهُ فَقَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يكبرها. رَوَاهُ مُسلم
sunnah.com