Chapter of Ta'qeeb (Prayer Supplications)
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 47
قَالَ زُرَارَةُ سَمِعْتُ أَبَا جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ يَقُولُ: «اَلدُّعَاءُ بَعْدَ اَلْفَرِيضَةِ أَفْضَلُ مِنَ اَلصَّلاَةِ تَنَفُّلاً.
Zurarah reported that he heard Abu Ja'far عليه السلام say: "Supplication after the obligatory prayer is better than offering a voluntary prayer." And thus, this has been the practice.
- Ṣaḥīḥ al-Faqīh, p. 45