You can find Abraham’s confessions in his story in Genesis 23:1–20. There you read that Abraham confesses he is a stranger, who knows that he is dependent on the local people. Hebrews 11:13 is a quote from Psalm 39:1–13. (Read the whole psalm to understand what is meant here.)
In Psalm 39:13 David confesses he is dependent on God like a foreigner is dependent on the benevolence of the people in a strange country. The other word used for stranger
in Psalm 39:12 stresses that the person only stays for a while; a stranger is a temporary guest. Thus, in Psalm 39:1–13 David prays urgently for God’s help because he is (1) dependent on God and (2) he is only here on earth for a short while.
13 These all died in faith, not having received the things promised, but having seen them and greeted them from afar, and having acknowledged that they were strangers and exiles on the earth.