Al-Kāfi
Hadith 8505- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ صَفْوَانَ عَنْ إِسْحَاقَ بْنِ عَمَّارٍ قَالَ قُلْتُ لأبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) إِنِّي جَعَلْتُ عَلَى نَفْسِي شُكْراً للهِ رَكْعَتَيْنِ أُصَلِّيهِمَا فِي الْحَضَرِ وَالسَّفَرِ أَفَأُصَلِّيهِمَا فِي السَّفَرِ بِالنَّهَارِ فَقَالَ نَعَمْ ثُمَّ قَالَ إِنِّي أَكْرَهُ الإيجَابَ أَنْ يُوجِبَ الرَّجُلُ عَلَى نَفْسِهِ قُلْتُ إِنِّي لَمْ أَجْعَلْهُمَا للهِ عَلَيَّ إِنَّمَا جَعَلْتُ ذَلِكَ عَلَى نَفْسِي أُصَلِّيهِمَا شُكْراً للهِ وَلَمْ أُوجِبْهُمَا عَلَى نَفْسِي أَفَأَدَعُهُمَا إِذَا شِئْتُ قَالَ نَعَمْ.
5. Ali ibn Ibrahim has narrated from his father from Safwan from Ishaq ibn ‘Ammar who has narrated the following: “I once said to abu ‘Abd Allah (a.s.), ‘I have made it upon myself to perform two Rak‘at Salat (prayer) as thanksgiving to Allah at home or on a journey’ if on a journey I can perform them during the day. He (the Imam) said, ‘Yes, you can do so.’ He (the Imam) then said, ‘I dislike a man’s making it obligatory upon himself.’ I then said, ‘I have not made them for Allah but I have made it upon myself to perform the two Rak‘at to thank Allah and I have not made it obligatory on myself if I can stop performing them when I wanted. He (the Imam) said, ‘Yes, you can do so.’”