Since God is “the Source from whom all blessings flow,” how can we bless Him?

Question:
In Hebrews 7:7 it is said, “The less is blessed of the better.” In, I think, the Psalms, phrases as, “Bless the Lord O my soul” occur. If God is “the Source from whom all blessings flow” (He is), how can we bless Him?

Answer:
There are similar but different meanings to the word “bless.” And it depends on the context where the word is found as to what is meant when the word “bless” is used.

The first meaning of the word “bless” is “to praise, celebrate with praise, and acknowledge God’s goodness with desire for His glory.” The second meaning of the word “bless” is “to invoke or give blessing to a person.”
The Psalmist in Psalm 103, 104, etc. was praising, celebrating, and acknowledging “all His [the Lord’s] benefits” (Psalm 103:2), which is the first meaning mentioned above.
The second meaning is seen in what the Lord desires His disciples to do. “But I say unto you which hear, love your enemies, do good to them which hate you, bless them that curse you, and pray for them which despitefully use you” (Luke 6:27,28). To invoke or give blessing would be to tell them in love that you want their good, and pray for them. Instead of cursing, the Lord wants us to bless even those who curse us.
It is easy to see that we can bless God in the first meaning of the word “bless” for He is worthy of our praise for all He has done for us, but can we invoke or give blessing to God, who is certainly better than we are?
One thing is certain: we cannot give anything that we do not have to give, and we have nothing but what we have received from God (1 Corinthians 4:7). But God made our mouths (Exodus 4:11), and He made every part of us to praise Him (Isaiah 43:21). Someday in the glory we will see that all things were created by Him, and for His pleasure (Revelation 4:11). So He gets pleasure from even our praise.