According to the heading of the psalm, David composed it to be sung when the memorial offering was made (the memorial offering was part of the grain offering). The psalm is almost the same as Psalm 40:13-17. We cannot tell why these verses of Psalm 40 have been more or less repeated, although it is reasonable to think that the composer realised that they contained suitable themes for reflection when making the memorial offering. One difference between Psalm 70 and Psalm 40 is that the pleas in Psalm 70 are more urgent.
David wants each worshipper, when presenting his memorial offering, to ask God to remember him quickly if he was under attack. Usually such a person was in trouble, facing danger from his opponents, even as in this case death. His only refuge was the Lord, a reality that God’s people often go through. Asking the Lord for help is a strong expression of faith. It is a sign of little self-confidence and of great God-confidence. Asking the Lord for help is also a sign of wisdom, evidence that we know about his abilities. Such asking is the outcome of previous experiences when we discovered the Lord’s faithfulness to those who trust in him. Since he helped before, he will help again and again.
Further, when making the memorial offering David wants the worshipper to remember all of God’s people (v. 4). No doubt, the worshipper could see many of them in the temple as he made his offering and it was easy, in a sense, to remember to pray for them. David desired the spiritual progress of other believers and he did not allow his personal circumstances to prevent expressions of brotherly love. He also reveals the priority for believers – to rejoice in God and praise him for his saving grace. So the psalmist prayed that joyful worship would take place even although he himself was feeling sad and isolated.
David also wants the worshipper, when presenting the memorial offering, to affirm his faith in God by expecting his help (v. 5). The psalmist realises that in himself he is weak and fragile, but he has learned to use his weaknesses as arguments in prayer to God. Embarrassment did not keep him from admitting his weakness, which it often can do in everyday situations. David had learned that the Lord helps the helpless and can rescue them from whatever difficulties that are overwhelming them.
Of course, we don’t have to engage in a sacrificial ritual when asking God to remember us. Yet when praying for ourselves we must remember to pray for others.