Hebrews 11:16

But now they desire a better country, that is, a heavenly: wherefore God is not ashamed of them, to be called their God; for he hath prepared for them a city.

The implicit trust of Abraham, Isaac, and Jacob in all that God had promised, along with their accounting themselves strangers and pilgrims, was well-pleasing to God; and God was not ashamed of them (although, judged in regard to some of their sinful actions, God might well have had ample reason to be ashamed of some of them), even consenting to be known historically as "the God of Abraham, and the God of Isaac, and the God of Jacob" (Exodus 3:6).

For he hath prepared for them a city is in the prophetic tense; that is, a future thing that God will do is spoken of as already done. Another example is "I loved him and called my son out of Egypt" (Hosea 11:1). Speaking of the same city mentioned here, long centuries afterward, Jesus said, "I go to prepare a place for you" (John 14:2). That the city of the redeemed, mentioned by Jesus, and the one mentioned here as the inheritance of the patriarchs, are only one city, and not two, is evident from Luke 13:28ff.

God's not being ashamed of his servants is, of course, contingent upon their not being ashamed of God, nor of Christ, nor of the gospel, nor of the church, nor of anything the Lord has taught in the scripture. See Romans 1:16; 2 Timothy 1:8; and Mark 8:38.