'Testify' in the Bible

It shall come about if you ever forget the Lord your God and go after other gods and serve them and worship them, I testify against you today that you will surely perish.

Then it shall come about, when many evils and troubles have come upon them, that this song will testify before them as a witness (for it shall not be forgotten from the lips of their descendants); for I know their intent which they are developing today, before I have brought them into the land which I swore.”