Charles H. Spurgeon on Psalms 105:42

For he remembered his holy promise, and Abraham his servant. Here is the secret reason for all this grace. The covenant and he for whose sake it was made are ever on the heart of the Most High. He remembered his people because he remembered his covenant. He could not violate that gracious compact for it was sacred to him, —"his holy promise." A holy God must keep his promise holy. In our case the Lord's eye is upon his beloved Son, and his engagements with him. On our behalf, and this is the source and well ahead of those innumerable favours which enrich us in all our wanderings through this life's wilderness.