Al-Kāfi

Hadith 778
mourning-condolence
4ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ خَالِدٍ عَنْ أَبِيهِ عَنْ بَعْضِ أَصْحَابِهِ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ التَّعْزِيَةُ الْوَاجِبَةُ بَعْدَ الدَّفْنِ.
4. A number of our people have narrated from Ahmad ibn Muhammad ibn Khalid from his father from certain persons of his people who has said the following: “Abu ‘Abd Allah (a.s.), has said that the necessary condolence should be offered after burial takes place.”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī