Methuselah is mentioned in Genesis 5:21-27.
Methuselah is the longest lived person in the Bible - excluding, of course, the lord Jesus Christ who is now immortal. When Methusaleh died he had lived 969 years. The fact that he was the father of Lamech who was the father of Noah indicates that he was a God-fearing man. However, we are not told explicitly about Methusaleh's standing before God.
I hope you have found this helpful.
God bless,
Mike