Is it true that a person without a mustache cannot have his testimony accepted, and was this narrated from the Messenger of Allah (peace be upon him) or from any of the scholars and jurists? And what is the proof for that if it is true?

Scholars differed concerning the ruling on completely shaving the mustache. The Hanafis have two opinions: trimming or shaving. The Malikis, however, deemed shaving it unlawful and held that the one who does so should be disciplined. The Shafi'is, on the other hand, prohibited shaving it completely, stating that the Sunnah is to trim it until the edge of the lip becomes visible.

The evidence for those who permitted shaving is the hadiths: "Trim the mustaches" and "Shorten the mustaches," interpreting these words as referring to complete removal. Conversely, the evidence for those who prohibited complete removal is their interpretation of these terms as trimming only what exceeds the edge of the lip.

The disagreement on this issue is strong, and some scholars offered a choice between the two matters. The more preponderant view is that trimming is preferable to shaving, as the narration "trimming the mustache" is mentioned in the hadith of Fitra.