1 Samuel 3:8

“And the Lord called Samuel again the third time, etc.] In the same manner he had done before, expressing his name no doubt: and he arose and went to Eli, and said, here am I, for thou didst call me; as if he should say, it must certainly be so, I cannot be mistaken a third time: and Eli perceived that the Lord had called the child; he was satisfied now that Samuel must have heard a voice, and he knew there was no man in the tabernacle but himself, and therefore it must be the voice of the Lord out of the most holy place; and he had formerly been acquainted with such voices, and used to them, and now called them to mind; and besides, as Aben Ezra observes, he was the rather confirmed in this,…”

“3:8 Eli realized: Despite his many shortcomings, Eli was not completely without spiritual insight.”

“the third: Job 33:14, Job 33:15; Although Samuel did not apprehend the way in which God reveals himself to his servants the prophets - by the "still small voice" - yet when this direct communication from the Almighty was made the third time, in a way altogether new and strange to him, it seems astonishing that he did not immediately apprehend. Perhaps he would have been sooner aware of a divine revelation, had it come in a dream or a vision. Those who have the greatest knowledge of divine things, should remember the time when they were as babes, unskilful in the word of righteousness. Co1 13:11, Co1 13:12 1 Kings (1 Samuel) 3:9”