It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that he reports this saying of the Prophet (peace and blessings be upon him): "Acquire the knowledge of the Qur'an from four people: Ubayy bin Ka'b, Abdullah bin Mas'ud, Mu'adh bin Jabal, and Salim, the freed slave of Abu Hudhayfah."
Al-Bazzar recorded it, and its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15710