Luke 17: 1 - 6
1 And he said to his disciples, "Temptations to sin are sure to come; but woe to him by whom they come!
2 It would be better for him if a millstone were hung round his neck and he were cast into the sea, than that he should cause one of these little ones to sin.
3 Take heed to yourselves; if your brother sins, rebuke him, and if he repents, forgive him;
4 and if he sins against you seven times in the day, and turns to you seven times, and says, `I repent,' you must forgive him."
5 The apostles said to the Lord, "Increase our faith!"
6 And the Lord said, "If you had faith as a grain of mustard seed, you could say to this sycamine tree, `Be rooted up, and be planted in the sea,' and it would obey you.

EWTN