Today's Gospel reading from Matthew is about Peter the Rock and First Prophecy of Passion and Resurrection. Jesus was preparing to build his church on Peter. When the Lord prophesied that he's going to suffer and be put to death, Peter began to remonstrate with him and he responded, "Get out of my sight, you satan! You are trying to make me trip and fall. You are not judging by God's standards but by man's." Strong words. We could see that Jesus was cleaning Peter's heart.
This made me think how necessary it is to have a clean heart. We all like to live in a clean house or neighborhood, sleep on clean sheets in bed, eat on clean plates, etc. To have a clean heart is to feel even better because we know now that the Holy Spirit is happy to dwell in it, readying us for doing God's work. A perfect time to ask for a clean heart is when we lift up our hearts to the Lord during Eucharistic Prayer.