When the approach of death is sensed, one needs to exert oneself immensely in Tasbih and Istighfar
Verse An-Nasr 110:3 ⧉ فَسَبِّحْ بِحَمْدِ رَبِّكَ وَاسْتَغْفِرْهُ (then pronounce the purity and praise of your Lord, and seek forgiveness from Him...) Sayyidah ` A'ishah Siddiqah ؓ says that after the revelation of this Surah, whenever the Messenger of Allah ﷺ performed a prayer, he would recite the following supplication: سُبحَانَکَ رَبَّنَا و بِحَمدِکَ اللَّھُمَّ اَغفِرلِی (I pronounce Your purity, 0 Allah, our Lord, and praise be to You, 0 Allah, forgive me.) [ Bukhari ].
Sayyidah 'Umm Salamah ؓ says that after the revelation of this Surah, the Messenger of Allah ﷺ used to often recite the following supplication: سُبحَانَ اللہِ وَ بِحَمدِہٖ اَستغفِرُ اللہَ وَ اَتُوبُ اِلیہِ (I pronounce the purity of Allah, and praise be to Him. I seek Allah's forgiveness and I repent to Him.) He used to say, "I have been commanded to do so." In evidence, he used to recite this Surah.
Sayyidna Abu Hurairah ؓ says that after the revelation of this Surah, the Messenger of Allah ﷺ used to exert himself in the worship of Allah so immensely that his feet would swell. [ Qurtubi ].