From page 736 of Deathly Hallows:
He changed course, running at Bellatrix rather than Voldemort, but before he had gone a few steps he was knocked sideways.
"NOT MY DAUGHTER, YOU BITCH!"
Mrs. Weasley threw off her cloak as she ran, freeing her arms. Bellatrix spun on the spot, roaring with laugher at the sight of her new challenger.
"OUT OF MY WAY!" shouted Mrs. Weasley to the three girls, and with a swipe of her wand she began to duel.
...
"You - will - never - touch - our - children - again!"
screamed Mrs. Weasley.
Bellatrix laughed, the same exhilarated laugh her cousin Sirius had given as he toppled backward through the veil, and suddenly Harry knew what was going to happen before it did.
Molly's curse soared beneath Bellatrix's outstretched ar