Hadithcore
Mishkat al-Masabih, 4058

Ibn ‘Umar told that he saw the first thing God’s Messenger did immediately anything came to him was to give something to those who had been set free. Abu Dawud transmitted it.

وَعَنِ ابْنِ عُمَرَ قَالَ: رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَوَّلُ مَا جَاءَهُ شيءٌ بدَأَ بالمحرَّرينَ. رَوَاهُ أَبُو دَاوُد

References1 variant
In-Book Reference
Book 19, Hadith 268