Al-Kāfi

Hadith 1977
congregational-prayermosque
6ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ عَلِيِّ بْنِ الْحَكَمِ عَنِ الْحُسَيْنِ بْنِ الْمُخْتَارِ عَنْ أَبِي إِبْرَاهِيمَ (عَلَيْهِ السَّلاَم) قَالَ قُلْتُ لَهُ إِنَّا إِذَا دَخَلْنَا مَكَّةَ وَالْمَدِينَةَ نُتِمُّ أَوْ نَقْصُرُ قَالَ إِنْ قَصَرْتَ فَذَاكَ وَإِنْ أَتْمَمْتَ فَهُوَ خَيْرٌ يَزْدَادُ.
6. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Ali ibn al-Hakam from Al-Husayn ibn al-Mukhtar who has said the following: “I once asked abu Ibrahim (a.s.), ‘When we enter Makkah or al-Madinah, should we perform Salat (prayer) in complete or reduced form?’ He (the Imam) said, ‘If you perform in reduced form it is what it is; and if you perform in complete form it, then is an increasing good.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī