Does a weak hadith become stronger through multiple chains of narration, reaching the level of hasan?

The questioner : The second part asks: if the hadith itself is narrated through several chains—so-and-so narrated from so-and-so through several chains, and so on—and it is found that this weak hadith has several chains, it is said that this reaches the level of hasan. Is this correct, O Shaykh?

The Shaykh : Yes, this is correct, but with some explanation and detail that is necessary. In fact, I say it may reach the level of sahih, not just hasan. But we must explain the idea of the scholars who held this view, and then their evidence for it.
First: this general statement, meaning that a weak hadith is strengthened by the multiplicity of chains, is not absolute. It has a condition, which is: if the weakness of the chains is not severe. This requires explanation in the terminology of hadith scholars. What does it mean that the weakness of the chains is not severe? And what is the outcome of this condition?
Its outcome, in very brief and concise summary, is that the weakness must result from the poor memory of one of the narrators. Because this narrator with poor memory, if he narrates a hadith alone, may have made a mistake in it. And mistakes are of different types—and this is, of course, explained in hadith books in a way that no further explanation is needed. A narrator with poor memory may take a statement from a Companion and mistakenly attribute it to the Messenger of Allah (peace and blessings be upon him), or the reverse: the hadith is from the Companion about the Messenger of Allah (peace and blessings be upon him), but he forgets and says, "So-and-so the Companion said," and so on. There are many examples.
So the condition here, "if its weakness is not severe," means that these chains revolve around narrators who are all trustworthy, upright, and sound, and do not lie. But every chain contains a man with poor memory. In that case—it is theoretically possible—that the one with poor memory narrates a hadith containing a mistake that has not been detected. What is our position regarding his hadith? We must distance ourselves from it, because we do not narrate a hadith or attribute it to the Messenger (peace and blessings be upon him) until we have a preponderance of probability that he said it—as explained previously. The narration of a weak hadith by one with poor memory does not achieve a preponderance of probability in the researcher's mind that the Messenger (peace and blessings be upon him) said this; on the contrary.
Therefore, scholars avoid the hadith of the truthful but poor-memorizing narrator... it is not used as evidence. But a truthful one, plus another truthful one—another chain—plus another truthful one—a third chain—and so on according to the hadith and its chains, the doubt that prevents hadith scholars from using the hadith of the poor-memorizing narrator as evidence is removed. Why? Because how could this one make a mistake, and that one make a mistake, and that one make a mistake? That is very far-fetched.
Some scholars give an example: suppose a skilled poet composes a poem of four or five verses. It is impossible for another poet to compose the same meaning with the same words used by the first poet. It is impossible; he may perhaps hum around the meaning, but with different wording and a different rhyme. So, the combination of a weak one with a weak one, as it is said:
"Do not fight my heart with your eyes, *** For two weak ones overcome a strong one."
If three or four of the weak ones gather, they give strength to this narration. Then the evidence of the scholars for this rule, after clarifying it and explaining the condition in it, is that Allah the Exalted made the testimony of two women equivalent to the testimony of one man. And He said in the explanation of the ruling: So the testimony of a woman is half the testimony of a man, because the woman has special circumstances unlike the man. So the Lord of the worlds supported this innate weakness present in the woman with the testimony of another woman. Thus, two women equal the testimony of one man. Therefore, two weak ones of the aforementioned type equal the narration of a trustworthy one. With this condition, a weak hadith, if its chains are numerous and these chains are not severely weak, it moves to the level of hasan. In fact, it may rise to the level of sahih as the chains multiply, because the multiplication of chains strengthens the probability that was cast into the mind from the two or three chains.