Al-Kāfi - Volume 6 > Preparation of Food for a Ceremony, like Wedding and so forth
Hadith #2

أَحْمَدُ بْنُ مُحَمَّدٍ عَنِ الْهَيْثَمِ بْنِ أَبِي مَسْرُوقٍ عَنْ هِشَامِ بْنِ سَالِمٍ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) أَنَّهُ قَالَ لَا تَجِبُ الدَّعْوَةُ إِلَّا فِي أَرْبَعٍ الْعُرْسِ وَ الْخُرْسِ وَ الْإِيَابِ وَ الْإِعْذَارِ .

2. Ahmad ibn Muhammad has narrated from al-Haytham ibn abu Masruq from Hisham ibn Salim who has said the following: “Inviting (people for food) is not obligatory except for four occasions. Such occasions are: weddings, the birth of a child, circumcisions, and returning from a journey.’”