Muwatta Imam Malik Book of I'tikaf in Ramadan, Hadith 6

Yahya related to me from Ziyad from Malik that he saw some of the people of knowledge who, when they did itikaf in the last ten days of Ramadan, would not go back to their families until they had attended the Id al-Fitr with everybody.
Ziyad said that Malik said, "I heard this from the people of excellence who have passed away, and it is what I like most out of what I have heard about the matter."

حَدَّثَنِي يَحْيَى عَنْ زِيَادٍ عَنْ مَالِكٍ أَنَّهُ رَأَى بَعْضَ أَهْلِ الْعِلْمِ إِذَا اعْتَكَفُوا الْعَشْرَ الأَوَاخِرَ مِنْ رَمَضَانَ لاَ يَرْجِعُونَ إِلَى أَهَالِيهِمْ حَتَّى يَشْهَدُوا الْفِطْرَ مَعَ النَّاسِ . قَالَ زِيَادٌ قَالَ مَالِكٌ وَبَلَغَنِي ذَلِكَ عَنْ أَهْلِ الْفَضْلِ الَّذِينَ مَضَوْا وَهَذَا أَحَبُّ مَا سَمِعْتُ إِلَىَّ فِي ذَلِكَ .