Psalm118:18 Ask and it shall be given unto you, seek and you shall find, knock and the door shall be open unto you.
I think that that is either Matthew 7:7 or Luke 11:9 rather than Psalm 118:18.
Yes, that's from the Sermon on the Mount!
Psalm118:18 Ask and it shall be given unto you, seek and you shall find, knock and the door shall be open unto you.