What is the ruling on saying "غير مغضوب عليهم" (not those who have incurred wrath) instead of "غير المغضوب عليهم" (not those who have incurred wrath) in Al-Fatihah, and is the prayer valid with that?

It is not permissible to say "غير مغضوب عليهم" (ghairi maghdoubi alayhim - not those who have incurred wrath) instead of {غَيْرِ الْمَغْضُوبِ عَلَيْهِمْ} (ghayril maghdoubi alayhim - not of those who have incurred wrath) in Surat Al-Fatihah, and this invalidates the prayer. This is because reciting Al-Fatihah is a pillar of prayer, and whoever omits a letter or a shaddah (doubling mark) from it is as if they have not recited it. Consequently, they have not fulfilled the pillar completely, and their prayer is not valid, unless they immediately correct the word.