O LORD, in your strength the king rejoices, and in your salvation how greatly he exults!  You have given him his heart’s desire and have not withheld the request of his lips. Selah  For you meet him with rich blessings; you set a crown of fine gold upon his head.  He asked life of you; you gave it to him, length of days forever and ever.  His glory is great through your salvation; splendor and majesty you bestow on him.  For you make him most blessed forever; you make him glad with the joy of your presence.  For the king trusts in the LORD, and through the steadfast love of the Most High he shall not be moved.  Your hand will find out all your enemies; your right hand will find out those who hate you.  You will make them as a blazing oven when you appear. The LORD will swallow them up in his wrath, and fire will consume them.  You will destroy their descendants from the earth, and their offspring from among the children of man.  Though they plan evil against you, though they devise mischief, they will not succeed.  For you will put them to flight; you will aim at their faces with your bows.  Be exalted, O LORD, in your strength! We will sing and praise your power. (Psalm 21 ESV)
God has kept his covenant with his people (5-7), in splendor and majesty and joy. He keeps his covenant out of his character, his steadfast love. God is a covenant-keeping God. He operates within his own character to take care of his people.
When the Most High gave to the nations their inheritance, when he divided mankind, he fixed the borders of the peoples according to the number of the sons of God. But the LORD’s portion is his people, Jacob his allotted heritage. (Deuteronomy 32:8-9 ESV)
How does the attribute of God as covenant keeper impact us? This means everything to us. The fact that God keeps his covenant with us is crucial since we understand salvation to be of the Lord, and not brought about by our efforts and work. This is held together because Jesus accomplishes everything he has set out to accomplish.
 That is why it depends on faith, in order that the promise may rest on grace and be guaranteed to all his offspring—not only to the adherent of the law but also to the one who shares the faith of Abraham, who is the father of us all,  as it is written, “I have made you the father of many nations”—in the presence of the God in whom he believed, who gives life to the dead and calls into existence the things that do not exist.  In hope he believed against hope, that he should become the father of many nations, as he had been told, “So shall your offspring be.”  He did not weaken in faith when he considered his own body, which was as good as dead (since he was about a hundred years old), or when he considered the barrenness of Sarah’s womb.  No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God,  fully convinced that God was able to do what he had promised.  That is why his faith was “counted to him as righteousness.”  But the words “it was counted to him” were not written for his sake alone,  but for ours also. It will be counted to us who believe in him who raised from the dead Jesus our Lord,  who was delivered up for our trespasses and raised for our justification. (Romans 4:16-25 ESV)