Does ablution become void when in doubt about covering the entire head with water during wiping, while being certain of wiping it? Is it obligatory to repeat the prayers that were performed with an ablution whose validity is doubted? Is it necessary to repeat the prayer if the worshiper unknowingly ate camel meat?

Wiping the head is a pillar of ablution, and doubting it after completing ablution has no effect. However, if the doubt occurs during ablution, it is assumed that the wiping was not comprehensive. It is permissible to follow those who do not obligate comprehensive wiping, such as the Shafi'is and Hanafis. Based on this opinion, there is no need to repeat prayers for which comprehensive head wiping was doubted. As for eating camel meat, it does not invalidate ablution according to the majority of scholars, and it is permissible to follow this opinion. Repeating the prayer, to avoid the difference of opinion, is closer to piety and caution.