One day I went on a website to check if I was pronouncing my prayer correctly, and I found out that I’ve been mispronouncing the last part of the prayer instead of saying ash hadu anna Muhammadan abduhu wa rasuluhu I said ash hadu anna Muhammadan abdul was rasuluhu. I’ve prayed many prayers while pronouncing this part this way, is my prayer invalid? I’ve heard that if you mispronounced a word in which it changes it’s meaning then your prayer is invalid. Is this true? Are my prayers invalid? I’ve also noticed I’ve made a mistake in the Fatiha, I’ve heard that it if you make mistakes in the Fatiha your prayer is invalid. Is this true if you thought you were saying the right thing and have been praying many prayers with this pronunciation. Do I have to repeat all my prayers? edit the mistake in the Fatiha was instead of say siratal I said salatal
Check out this website, I hope it can help with this! https://islamqa.info/en/answers/161424/she-used-to-pray-not-covered-properly-and-she-did-not-recite-al-faatihah-properly
On the authority of Ibn Abbas (may Allah be pleased with him), that the Messenger of Allah (peace and blessings of Allah be upon him) said:
Verily Allah has pardoned [or been lenient with] for me my ummah: their mistakes, their forgetfulness, and that which they have been forced to do under duress.
A hasan hadeeth related by Ibn Majah, and al-Bayhaqee and others.
Reference : 40 Hadith Nawawi 39