If a small, hard piece of human feces falls on a carpet without leaving any visible traces, and the carpet has been vacuumed many times afterwards, will it be permissible to pray on it? What if someone walked on said carpet with dry feet or socks? And if he/she continued to walk on another carpet after this, will it be permissible to pray on the second carpet?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.

If this question results from Waswaas (obsessive whisperings), then we advise you to totally disregard such whisperings. Please refer to Fataawa 83401 and 199253.

As for the relevant religious ruling, when hard pieces of human feces fall on a carpet, the ritual impurity is removed once those pieces are removed, whether by means of a vacuum cleaner or otherwise. The carpet does not become ritually impure when those hard pieces touch it because dry impurity is not transferred to pure dry items that come in contact with it. For more benefit, please refer to Fatwa 81546.

Allaah Knows best.