مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3487
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn ‘Abbas (رضي الله عنه) that al-Aqra` bin Habis asked the Messenger of Allah (ﷺ): ls Hajj every year? He said: "No, rather it is one Hajj, and whoever does Hajj after that, it is voluntary. If I said yes, it would become obligatory, and if it became obligatory, you would not listen and would not obey."
Musnad Ahmad 3510A saheeh hadeeth]