It is narrated from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him); he said: A man came to the Prophet (peace and blessings be upon him) and said: I have a nephew who does not refrain from unlawful things. He (peace and blessings be upon him) asked: "What is his religion?" He said: He prays and affirms the Oneness of Allah. He (peace and blessings be upon him) said: "Then ask him to give you his religion as a gift; if he refuses, buy it from him." So the man asked this of him, but he refused. The man came to the Prophet (peace and blessings be upon him), informed him and said: I found him miserly about his religion. At that, Allah, the Mighty and Majestic, revealed this verse: "Indeed, Allah does not forgive that partners be associated with Him, and He forgives what is less than that (of sins) for whom He wills" [Surah al-Nisa: 48].
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4048