comes from Dr. Luther's early Reformation piece, *The Babylonian Captivity.* Some helps in sorting it out:
"Woman who should bruise the serpent's head" is based on the old Vulgate reading of Genesis 3:15 where "she" (not "he") crushes the head. Medieval Christians took this as a reference to Mary. This was often depicted in art as in the picture in this post. Luther would later notice the problem as he translates the Hebrew and disagree with the Latin, siding with the Hebrew and the Greek translation: our Lord, not His mother, tramples the serpent!
"For such a promise, being the truth of God, preserves even in hell those who believe it and wait for it."
"Hell" here is not simply the place of torment for the unbelievers; it is the place of the dead - Hades, the place where BOTH the righteous dead and the unrighteous dead were kept - think of Lazarus and the Rich Man. Part of the early church's belief was that Christ descended to Hades, to Hell, in order to rescue these OT believers who were waited in faith for the day when the Promised Seed would descend to rescue them and bring them up with Him. This is what Luther refers to here. He also refers to this belief in his famous sermon for Holy Saturday in the House Postils - "rescuing the prisoners."
Read Hebrews 11 in light of this, especially vs. 13, 39, 40. Also our Lord's words to Nicodemus in John 3: "No one has ascended into heaven except He who descended from heaven, the Son of Man."
Hope that helps in sorting out the reading for the day!