Musnad Abu Ya'la al-Mawsili 209:131

Abu Khaythama narrated to us, Ya'qub ibn Ibrahim narrated to us, he said: My father narrated to me, from Ibn Ishaq, who said: Sulayman ibn Suhaym, the freed slave of the family of Hunayn, narrated to me, from Yahya ibn Abi Sufyan al-Akhnasi, from his mother, Umm Hakim bint Umayya ibn al-Akhnas, from Umm Salama, the wife of the Prophet, may Allah bless him and grant him peace, who said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "Whoever enters into the state of ihram for an 'Umrah or a Hajj from al-Masjid al-Aqsa, his past sins will be forgiven." She said: So Umm Hakim rode [to travel] because of that hadith to Bayt al-Maqdis, until she entered into the state of ihram for an 'Umrah from there.