Explanation of the author's statement: "…knowing the time…"

The Shaykh :"Knowing the time" This is a condition, not a non-condition. This is a condition, not a non-condition, because he must know. Ibn Umm Maktum was a blind man who did not call the adhan until it was said to him, "It is morning, it is morning." It is necessary for him to know the time. Knowing the time means knowing it by himself; this is the most complete and best way, because it may be difficult for him to find someone to inform him at the time of the adhan. Therefore, he should be the one who knows the time.