مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3543
Musnad of Abdullah bin Mas'ood
It was narrated from `Abdullah (رضي الله عنه) that The Prophet (ﷺ) prayed Zuhr with five rak'ahs. It was said: Has something been added to the prayer? And it was said: You prayed five (rak'ahs). And he prostrated twice.
Musnad Ahmad 3566Its isnad is saheeh, al-Bukhari (1226) and Muslim (572)]