Al-Kāfi
Hadith 16394ـ عَنْهُ عَنْ عُثْمَانَ بْنِ عِيسَى عَنْ سَمَاعَةَ قَالَ قَالَ أَبُو عَبْدِ الله (عَلَيهِ السَّلام) مَنْ سَرَّهُ أَنْ يُسْتَجَابَ لَهُ فِي الشِّدَّةِ فَلْيُكْثِرِ الدُّعَاءَ فِي الرَّخَاءِ.
4. It is narrated from him (narrator of the Hadith above) from ‘Uthman ibn ‘Isa from Sama’a who has said the following: “Abu ‘Abd Allah (a.s.) has said, ‘Whoever likes his prayers answered in difficult times should pray when he enjoys well-being and comfort.’”