Al-Mu'jam al-Awsat 4734 — The Mother of the Believers, Sayyidah Umm

The Mother of the Believers, Sayyidah Umm Salamah (may Allah be pleased with her), relates that before his death the Messenger of Allah (peace and blessings be upon him) used to recite this supplication frequently: 'Subhanaka Allahumma wa bihamdika, astaghfiruka wa atubu ilayk' (O Allah, You are glorified, with Your praise; I seek Your forgiveness and I turn to You in repentance). I said: "O Messenger of Allah! I see that you frequently recite 'Subhanaka Allahumma wa bihamdika, astaghfiruka wa atubu ilayk' (O Allah, You are glorified, with Your praise; I seek Your forgiveness and I turn to You in repentance)?" He (peace and blessings be upon him) said: "I have been commanded with a matter." Then he (peace and blessings be upon him) recited this surah: "When the help of Allah and the victory come."
Only Hafs narrated this hadith from Asim, and Sahl bin Uthman is alone in narrating it.