Is it permissible for a blind person to rely on estimation in determining the times of prayer?

The Shaykh : There is a valid opinion that it is valid, and for this reason the jurists said that if a blind person estimates and prays, he must repeat the prayer in all cases, even if he hit the time, because he is not qualified to estimate. This was before clocks were introduced. Yes, but there is a second opinion that if he hits the time, the prayer is valid, and this is the correct opinion, because if he hits the time, it is valid. Yes.