Is performing ablution (Wudu') before clipping one's nails considered an innovation (bid'ah), and is the one who does so sinful if they do it out of habit?

It is not legislated to perform ablution (wudu) or ritual bath (ghusl) before trimming nails, due to the absence of any religious proof for it. In fact, singling out an act of worship for this specific time without proof is considered an innovation (bid'ah). Sheikh al-Islam Ibn Taymiyyah issued a fatwa permitting the trimming of nails while in a state of ritual impurity (janabah), citing the Prophet's (peace and blessings be upon him) saying, "Indeed, a believer does not become impure," and the absence of any religious proof that it is disliked to remove hair or nails while in a state of janabah. The Hanafis disagreed with this, holding the view that it is disliked to shave hair or trim nails while in a state of janabah before performing the ritual bath.