Jami` at-Tirmidhi Book 48, Hadith 208
“My father narrated to me, from my grandfather, that he heard the Prophet (ﷺ) say: ‘Whoever says: “I seek forgiveness from Allah, the Magnificent, whom there is none worthy of worship but Him, the Living, Al-Qayyum, and I repent to him,” (Astaghfirullāhal-`Aẓīm alladhī lā ilāha illā huwal-Ḥayyul-Qayyūmu wa atūbu ilaih) then Allah will forgive him, even if he fled from battle.’”
“The Messenger of Allah (ﷺ) stayed with my father.” So he said: “We brought some food near him, so he ate from it, then he was brought dates, so he would eat it and cast the pit with his two fingers” - he joined between his forefinger and middle finger - Shu`bah said: “And that is what I think concerning it, if Allah wills.” - “and he cast the pit between two fingers, then he was brought drink, so he drank it and then passed it to the one on his right.” He said: “So my father said - as he took hold of the rein of his beast: ‘Supplicate for us.’ So he said: ‘O Allah, bless for them what You have provided them, and forgive them, and have mercy on them (Allāhumma bārik lahum fī mā razaqtahum waghfir lahum warḥamhum).’”
“Supplicate to Allah to heal me.” He (ﷺ) said: “If you wish I will supplicate for you, and if you wish, you can be patient, for that is better for you.” He said: “Then supplicate to Him.” He said: “So he ordered him to perform Wudu’ and to make his Wudu’ complete, and to supplicate with this supplication: ‘O Allah, I ask You and turn towards You by Your Prophet Muhammad (ﷺ), the Prophet of Mercy. Indeed, I have turned to my Lord, by means of You, concerning this need of mine, so that it can be resolved, so O Allah so accept his intercession for me (Allāhumma innī as’aluka wa atawajjahu ilaika binabiyyka Muḥammadin nabi-ir-raḥmati, innī tawajjahtu bika ila rabbī fī ḥājatī hādhihī lituqḍā lī, Allāhumma fashaffi`hu fīyya).’”