Assalaamu alaykum. Please elaborate on this hadith and inform me of its degree of authenticity. What does 'clean descendents' really mean? Prophet Muhammad, sallallaahu ‘alayhi wa sallam, said, "I come from a continuous line of clean fathers and always mothers."

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

We did not find a hadeeth with this exact wording. However, there is another hadeeth to this effect that reads, "He continued transferring me from the pure loins to the purified wombs..." This is part of a long hadeeth which some scholars attributed to Abu Nuʻaym in his book Al-Hilyah, and it was cited by Ibn Al-Jawzi in his book Al-Mawdhooʻaat (The Fabricated Narrations).

These statements are intended to show the pure and impeccable lineage of the Prophet, sallallaahu ‘alayhi wa sallam, as well as the fact that he was born of lawful marriage untainted by the illegitimate relations of the people of the Jaahiliyyah (pre-Islamic era of ignorance). There are some authentic ahaadeeth reported to that effect. For instance, Ibn Saʻd cited the following hadeeth in At-Tabaqaat: ʻAa’ishah narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said, "I was not born out of wedlock." [Al-Albaani: Hasan (good)]

Allah knows best.