Is it permissible to name a newborn female "Rahmah"?

It is permissible to name a daughter "Rahmah," but it is better to avoid it due to the meaning it carries, which the Prophet, peace be upon him, disliked when naming with names like "Rabaah," "Yasar," and "Aflah." This is because it could lead to disliked ill omens and superstition. This is indicated by what Muslim narrated in his Sahih from Samurah ibn Jundub, may Allah be pleased with him, that the Prophet, peace be upon him, said: "Do not name your boy Yasar, nor Rabaah, nor Najih, nor Aflah. For you will say, 'Is he there?' and he will not be, so one will say, 'No.'"

The Shafi'is and Hanbalis interpreted this prohibition as one of dislike (makruh), not absolute prohibition (haram). This is indicated by the fact that the Prophet, peace be upon him, had a boy named "Rabaah" and he did not change his name. Furthermore, the hadith narrated by Jabir ibn Abdullah, stating that the Prophet, peace be upon him, intended to prohibit these names then remained silent, is interpreted to mean that Jabir was unaware of the prohibition, and that the mentioned prohibition is one of dislike, not prohibition.

And Allah knows best.