Reference for Psalms 89:29

לְ֭עוֹלָ֗ם אשמור־[אֶשְׁמָר־] ל֣וֹ חַסְדִּ֑י וּ֝בְרִיתִ֗י נֶאֱמֶ֥נֶת לֽוֹ׃

For ever will I keep for him My mercy, And My covenant shall stand fast with him.