What is the ruling on taking clothes vowed to other than Allah by consensus, and does wearing them in prayer invalidate it if they are unlawful?

Vowing to other than Allah is major Shirk (polytheism), and whoever does it must repent and renew his Islam. As for using clothes vowed to other than Allah, there is no harm in it, unless one believes there is a blessing in them. This is unlike livestock slaughtered for other than Allah, which is forbidden to eat because it was dedicated to other than Allah. It is permissible to pray in these clothes because there is no evidence to prohibit benefiting from them, and the basic principle is permissibility.