Does not wearing underwear outside of the menstrual period reduce the reward for prayer, given that the entire body is covered during prayer?

The prayer of a woman who covers her entire body is valid, and the reward for her prayer increases by wearing undergarments and covering herself more extensively. Ibn Qudamah stated in "Al-Mughni" that praying in two garments or more offers more complete covering, citing the hadith of Umar, may Allah be pleased with him: "When Allah grants abundance, then be abundant. A man may gather his garments upon himself. A man may pray in an izar (waist-wrapper) and rida' (upper garment), in an izar and a qamis (shirt), in an izar and a qaba' (cloak), in trousers and a rida', in trousers and a qamis, in trousers and a qaba', in a tibban (short trousers) and a qamis." Abu Dawud narrated from Ibn Umar who said: The Messenger of Allah, may Allah's peace and blessings be upon him, said, or he said: Umar said: "If one of you has two garments, let him pray in them. If he has only one garment, let him use it as an izar and not wrap himself completely like the Jews." Al-Tamimi said: "One garment is sufficient, two garments are better, and four are most complete: a qamis, trousers, a turban, and an izar."