It's Act II Scene I in Much Ado About Nothing and Leonato and Beatrice are engaging in another round of witty bantering. During their verbal sparring Beatrice refers to the old proverb "God sends a curst cow short horns." What this means is that God gives an ill-tempered cow short horns so that she can't inflict damage on anyone. But the proverb, as Beatrice points out, doesn't say anything about a cow that is too ill-tempered. To such a creature, God will give no horns at all, as Leonato says:
So, by being too curst, God will send you no horns.
In her response to Leonato, Beatrice takes the word "horns" in a metaphorical sense to refer to husbands, as she soon makes clear:
Just, if he send me no husband, for the which blessing I am at him upon my knees every morning and evening.
Beatrice admits to being too ill-tempered to be given a husband by God, and that's just how she likes it. Indeed, so grateful is she for this blessing that she gets down on her knees to give thanks to the Almighty every morning and every evening.