What the Protestant thinks Saint Matthew wrote is this:
The Rosary is straight out of the pits of Hell. Jesus condemned vain repetition in Matthew 6:7.
Note, he uses the words "vain repetitions".
Here is that verse from a Catholic Bible:
And when you are praying, speak not much, as the heathens. For they think that in their much speaking they may be heard.
I am not reminded of repetitive prayers like Rosary or Jesus Prayer. I am reminded of people praying together, purporting to pray to God and in fact giving analyses of the problem so that others may join in. God does not need those analyses. He knows the problem beforehand. What he wants is the request or the praise, and repeating it is no sin.
La Clairière, Paris
All Souls' Day