Abu Umamah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever accepts Islam at the hands of a man, then his wala' belongs to that man."
Al-Bukhari said: Ja'far bin al-Zubayr al-Shami, narrating from al-Qasim, is matruk al-hadith (abandoned); they abandoned him. Mu'awiyah bin Yahya al-Sadafi also narrated it from al-Qasim, and Mu'awiyah bin Yahya is also da'if (weak) and is not used as evidence.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21464