when
1 Samuel 3:19
And Samuel grew, and the LORD was with him and let none of his words fall to the ground.
1 Samuel 3:20
And all Israel from Dan to Beer-sheba knew that Samuel was established as a prophet of the LORD.
Jeremiah 28:9
As for the prophet who prophesies peace, when the word of that prophet comes to pass, then it will be known that the LORD has truly sent the prophet."
shall
Ezekiel 2:5
And whether they hear or refuse to hear (for they are a rebellious house) they will know that there has been a prophet among them.
2 Kings 5:8
But when Eli'sha the man of God heard that the king of Israel had rent his clothes, he sent to the king, saying, "Why have you rent your clothes? Let him come now to me, that he may know that there is a prophet in Israel."
Luke 10:11
`Even the dust of your town that clings to our feet, we wipe off against you; nevertheless know this, that the kingdom of God has come near.'