"'Whoso readeth, let him understand.'"
"You are not reading the word of a human being but the Word of God, the Most High. He desires pupils who diligently note and observe what He says. Moreover, if it is well said that the letters of princes should be read three times because they must speak with deliberation in order not to be considered fools, how much more necessary it is for one to read the letters of God, that is, the Holy Scriptures, three, four, ten, a hundred, a thousand, and many thousand times. For God speaks with deliberation and weight, nay, He is the eternal Wisdom itself. Whoever does this becomes better and more learned from Scripture. Whoever does not do so learns nothing, nay, becomes the worse for it."
Martin Luther, inscribing and then commenting on Mt 24:15 ("let the reader understand") "in someone's Bible", as trans. Ewald M. Plass on pp. 79-80 of vol. 1 of What Luther says: an anthology (St. Louis, MO: Concordia Publishing House, 1959). = WA 48, 119, where there are the usual variants (since, presumably, Luther inscribed this in more than one?). Cf. Aland, Hilfsbuch, no. 695, on p. 163. The year given at WA 48, 119 is 1541.