First is, “Listen, Israel: Our god is the Lord; the Lord is One; and you must love your god the Lord with all your heart, life, purpose, and might.” Second is, “Love your neighbor like yourself.” No command is higher than these.
I just wrote on this recently, but it doesn’t matter how long ago it came up: If Jesus considers these commands to be the top two in the bible, they’re commands we ought to have memorized, and ought to be practicing.
They’re both bible quotes themselves: Loving God, the LORD, is from Deuteronomy 6.4-5, and loving neighbors is from Leviticus 19.18. Wouldn’t hurt to memorize those verses on their own. But the reason I suggest memorizing Jesus’s whole statement from Mark is to include Jesus’s endorsement,
“No command is higher than these.”