It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) said: "The right of wala' belongs only to the one who frees the slave." (Wala' refers to the inheritance of the freed slave.)
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4817
Hadith Gradingحکم دارالسلام:حديث صحيح، خ: 6759، وهذا إسناد ضعيف، ابن جريح مدلس وقد عنعن