Is it obligatory to trim the mustache every 40 days if it is almost full and has never been trimmed at all? And should only the long part be trimmed, or should it be completely trimmed, based on the hadith of Anas (may Allah be pleased with him): "A time limit was set for us regarding trimming the mustache, clipping the nails, plucking the armpit hair, and shaving the pubic hair, that we should not leave it for more than forty nights"?

The Hadith mentioned regarding the characteristics of the fitra (innate disposition) is authentic. It is recommended to perform these actions every Friday, or when needed, and these characteristics should not be left for more than forty days. Scholars have differed on how to trim the mustache; some held the view that only what extends over the lip should be trimmed, while others permitted shaving. However, the Malikis disliked shaving it and considered it an innovation. From this, it is understood that adopting either method is permissible.