Whenever Messenger of Allah ﷺ became ill, he used to recite the Muawidhatan (i.e. the last two surahs of the Qur'an) and blow his breath over himself (after their recitation ) and rubbed his hands over his body. So when he was afflicted with his fatal illness. I started reciting the Muawidhatan and blowing my breath over him as he used to do and then I rubbed the hand of the Prophet ﷺ over his body.
أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا اشْتَكَى نَفَثَ عَلَى نَفْسِهِ بِالْمُعَوِّذَاتِ وَمَسَحَ عَنْهُ بِيَدِهِ فَلَمَّا اشْتَكَى وَجَعَهُ الَّذِي تُوُفِّيَ فِيهِ طَفِقْتُ أَنْفِثُ عَلَى نَفْسِهِ بِالْمُعَوِّذَاتِ الَّتِي كَانَ يَنْفِثُ وَأَمْسَحُ بِيَدِ النَّبِيِّ ﷺ عَنْهُ