مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2622
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Moosa bin Salamah that he asked Ibn 'Abbas about praying in al-Batha', if one does not catch up with the prayer with the imam. He said: Two rak'ahs, the Sunnah of Abul-Qasim (ﷺ).
Musnad Ahmad 2637lts isnad is saheeh, Muslim (688)]