مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2862
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas (رضي الله عنه) that: The Prophet (ﷺ) stayed in Makkah tor seventeen days in the year of the conquest during which he prayed two rak'ahs. Abun-Nadr said: Shortening (the prayers), praying two ruk'ahs.
Musnad Ahmad 2883A saheeh hadeeth; this is a da'eef isnad]