مُوَطَّأُ مَالِكٍ
Muwatta Malik 707
I'tikaf in Ramadan
وَحَدَّثَنِي زِيَادٌ، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ سَعِيدَ بْنَ الْمُسَيَّبِ، كَانَ يَقُولُ مَنْ شَهِدَ الْعِشَاءَ مِنْ لَيْلَةِ الْقَدْرِ فَقَدْ أَخَذَ بِحَظِّهِ مِنْهَا .
Ziyad related to me from Malik that he had heard that Said ibn al-Musayyab used to say, "Whoever is present at isha on Laylat al-Qadr has taken his portion from it."
Arabic/English book reference: Book 19, Hadith 17