Al-Kāfi
Hadith 14753ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ هِشَامِ بْنِ سَالِمٍ عَنْ سُلَيْمَانَ بْنِ خَالِدٍ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ الْسَّلام) عَنْ رَجُلٍ دَخَلَ الْمَسْجِدَ وَافْتَتَحَ الصَّلاَةَ فَبَيْنَا هُوَ قَائِمٌ يُصَلِّي إِذَا أَذَّنَ الْمُؤَذِّنُ وَأَقَامَ الصَّلاَةَ قَالَ فَلْيُصَلِّ رَكْعَتَيْنِ ثُمَّ لْيَسْتَأْنِفِ الصَّلاَةَ مَعَ الإِمَامِ وَلْتَكُنِ الرَّكْعَتَانِ تَطَوُّعاً.
3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Ibn Abi ‘Umayr from Hisham ibn Salim from Sulayman ibn Khalid who has said the following: “I once asked abu ‘Abd Allah (a.s.), about a man who enters Masjid and begins Salah (prayer). While he is standing up in Salah (prayer) Adhan is said and Salah (prayer) begins. He (the Imam) said, ‘He can perform it as a two Rak‘at, then commence Salah (prayer) with the Imam and the two Rak‘at has to be optional Salah (prayer)”’