Musnad Ahmad 293:2

Abu al-Mughirah narrated to us, he said: al-Awza'i narrated to us, he said: Yahya ibn Abi Kathir narrated to us, from Hilal ibn Abi Maymunah, from 'Ata' ibn Yasar, from Rifa'ah ibn 'Arrabah al-Juhani, who said: We departed with the Messenger of Allah, may Allah bless him and grant him peace, from Makkah, and the people began to ask his permission [to leave]. He mentioned the hadith. He said: Abu Bakr said: "Indeed, the one who asks your permission after this is, in my opinion, a fool." Then the Prophet, may Allah bless him and grant him peace, praised Allah and said what was good, then said: "I bear witness before Allah." And when he would swear an oath, he would say: "By the One in Whose hand is the soul of Muhammad, there is no servant who believes in Allah, then acts uprightly, except that he will be led into Paradise." He then mentioned the hadith.