'Covenant and Mercy' in the Bible

Understand, therefore, that the LORD thy God, he is God: and that a true God, which keepeth covenant and mercy unto them that love him and keep his commandments, even throughout a thousand generations;

and said, "O LORD God of heaven, thou great and terrible God, thou that keepest covenant and mercy for them that love thee and observe thy commandments:

Now our God, thou great God, mighty and terrible, thou that keepest covenant and mercy, regard not a little all the travail that hath happened unto us, and our kings, princes, priests, prophets, fathers and all thy people, since the time of the kings of Assyria unto this day.

I prayed before the LORD my God, and knowledged, saying, "O LORD, thou great and fearful God, thou that keepest covenant and mercy with them which love thee, and do thy commandments: