Psalm 119:11; David said, “Your words have I hidden in my heart, so I might not sin against You.” (‘Hidden in my heart’ just HAS to mean that I’ve memorized it.)
Deut. 6:6, Moses said, as a part of the Jewish Creed, the Shemah, “These Words shall be in your heart.” (as in “I know that by heart, I’ve memorized it.”)
Joshua 1:8; Joshua says, “This Book of the Law (God’s Word) shall not depart out of your mouth, but you shall meditate on it both day and night, so you can do all that is written in it.” (I bet if you meditate on something day and night, you’ll memorize it without even trying.)
Psalm 1:2; David says, [God’s man] “His delight is in the law of the Lord, and in His law he meditates both day and night.” (same as Joshua)
Hebrews 4:12-13; “The Word of God is quick (alive) and powerful, sharper that any two-edged sword, piercing, to the dividing in two, of the soul and the spirit, the joints and the marrow, and is a discerner of the thoughts and intents of the heart.”
I’ve got a theory. If God’s Word is like what it says in Heb. 4:12, and we hide God’s Word in our heart, (memorize it) then the discernment that is in His Word is in our hearts, and we can see, on some level, the thoughts and the intents of peoples’ hearts; (not just other peoples’ hearts, but also our own.) I’m sure there are a lot of wise, scholarly pastors and teachers of God’s Word who would disagree with me, but if the Holy Spirit of the Living God is dwelling in us, then it seems reasonable to believe, even trust, that the discernment of the Living God could and would be dwelling in us as well. For me, this is a very BIG reason for us to memorize scripture. Because if we can discern the thoughts and intentions of peoples’ hearts, then we can know what we really need to pray for, for them. Our intercession goes waaay up on the effectiveness scale.
Someone said that the reason we pray is for us to get to know God, for Himself, not just for what He can do. Hiding God’s Word in our hearts and meditating on those Words both day and night, will surely draw us closer to God and allow us to know Him better.