Nafi' relates about Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that it was said to him: You praise Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) greatly. He said: Why should I not do so, when I heard the Prophet (peace and blessings be upon him) say: "Learn the Qur'an from four people: Abdullah bin Mas'ud, Salim the freed slave of Abu Hudhayfah, Ubayy bin Ka'b and Mu'adh bin Jabal." Then the Prophet (peace and blessings be upon him) said: I intended to send them to various peoples, just as Sayyiduna Isa bin Maryam (peace be upon him) sent the disciples. It was said: O Messenger of Allah! Why do you not send Sayyiduna Abu Bakr (may Allah be pleased with him) and Sayyiduna Umar (may Allah be pleased with him)? They are both more virtuous. The Prophet (peace and blessings be upon him) said: I cannot do without them. The standing of these two in the religion is that of hearing and sight in the head."
Al-Tabarani recorded it in al-Mu'jam al-Awsat. Its chain contains a narrator, Hammad bin Umar al-Nasibi, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14933