Imam Muhammad bin Sirin, may Allah have mercy on him, said: The hadith you narrated to me, do not narrate it through these two men anymore because they do not care from whom they are taking the hadith. Imam Darimi said: I am not certain that Jarir heard this from Asim.

Ibrahim Nakha'i, may Allah have mercy on him, said: When you narrate a hadith from me, narrate it through the way of Abu Zur'ah, may Allah have mercy on him, because he narrated a hadith to me, then after a year I asked him about the same hadith, and he had not omitted even a single letter from it.

Imam Muhammad bin Sirin, may Allah have mercy on him, said: This knowledge (Hadith) is religion, so a person should be careful from whom he is taking his religion.

Ibrahim al-Nakha'i, may Allah have mercy on him, said: (The righteous predecessors) when they went to someone to take knowledge of hadith, they would carefully observe his prayer, manner, and appearance. Then they would take hadith from him.

Ibrahim al-Nakha'i, may Allah have mercy on him, said: When they (i.e., the righteous predecessors) would come to a man from whom they wanted to take knowledge, they would observe his prayer, conduct, and appearance, then they would take knowledge from him.

Hasan al-Basri (may Allah have mercy on him) also narrated in the same manner as Ibrahim (may Allah have mercy on him).

Abu Al-Aliyah said: We used to go to a man to take narration from him, so when he prayed, we would observe him; if he performed the prayer properly, we would sit down and say, "He will be good in matters other than prayer as well." And if he did not perform the prayer properly, we would get up from him and say, "He will be even worse in matters other than prayer." Abu Muammar said: These are his exact words.

Imam Muhammad bin Sirin, may Allah have mercy on him, said: This knowledge (the knowledge of the chain of narration of hadith) is religion, so look from whom you are taking your religion.

Sulaiman bin Musa said: I said to Imam Tawus, may Allah have mercy on him, that such-and-such a person narrated a hadith in this manner. He replied: If your narrator is wealthy, then take narration from him.

Imam Tawus, may Allah have mercy on him, said: Bishr bin Ka’b came to Sayyiduna Abdullah bin Abbas, may Allah be pleased with them both, and began narrating hadith. Sayyiduna Ibn Abbas, may Allah be pleased with them both, said: Recite the first hadith to me again. Bishr said to him: I do not know whether you considered all my ahadith to be correct except the first one, or you considered the first hadith to be correct and the rest not correct? Sayyiduna Ibn Abbas, may Allah be pleased with them both, said: We used to narrate hadith from the Messenger of Allah, peace and blessings be upon him, at a time when lies were not attributed to him. Then, when people became involved in both truth and falsehood (i.e., mixing lies with truth), we stopped narrating hadith from him. (That is, when people began attributing lies to the Messenger of Allah, peace and blessings be upon him, we became cautious and began to investigate the narrator.)