Hadith
أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا مَالِكٌ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ الْوَلاَءِ وَعَنْ هِبَتِهِ .
It was narrated from Ibn 'Umar that:the Messenger of Allah forbade selling loyalty or giving it away. (Shah)
Sahih · Abu Ghuddah
Sunan an-Nasa'i 4658 ·Book 44, Hadith 210·Also available on sunnah.com·