'A'ishah (RAA) narrated that The Messenger of Allah (ﷺ) said:
"Wala' is (legally) for the manumitter." Agreed upon. It is part of a long Hadith (refer to hadith no. 811). (DE)
English reference (DE): Book 15, Hadith 1472 (DE)
Arabic reference (DE): Book 15, Hadith 1428 (DE)