By Carol Glatz Catholic News Service VATICAN CITY (CNS) -- Don't hold back when praying to God -- tell him exactly what's wrong and insist on holding him to his promises, Pope Francis said. Prayer should be like speaking face-to-face with a friend: "without fear, freely and also with insistence," the pope said in his homily April 3 during an early morning Mass in the chapel of the Domus Sanctae Marthae. Pope Francis' homily focused on the day's reading from the Book of Exodus (32:7-14), in which Moses begs God to spare his people, even though they have created a golden calf to worship as their god. God says he's going to let his wrath "blaze up against them to consume them," but Moses reminds the Lord that these are his own people he has saved before and has promised to make their descendents "as numerous as the stars in the sky." Pope Francis said that, in the day's reading, Moses shows what praying to God should really feel and sound like: not filled with empty words, but a heartfelt, "real fight with God." Moses is courageously insistent and argues his point, the pope said, and prayer must also be "a negotiation with God, presenting arguments" supporting one's position. When God decides to not punish his people, it's not God who has changed, but Moses, the pope said. By freely talking out the problem and underlining all the ways God has always shown his mercy, Moses was able to rediscover, deep in his heart, what his head already "more or less sort of knew." "Prayer changes our hearts. It helps us better understand what our God is like," it helps people grow closer to him, recognize his love and rejuvenate one's faith. The pope underlined what Jesus said: "In praying, do not babble like the pagans, who think that they will be heard because of their many words." "No, say what's what: 'Look, Lord, I have this problem, in my family, with my child, with this, with that ... What can you do? Now see here, you can't leave me like this!' This is prayer. And does this prayer take a long time? Yes, it takes time." Pray like Moses did, face-to-face with the Lord, like a friend, freely, with insistence and good arguments, the pope said. "And also scold the Lord a little: 'Hey, you promised me this, and you haven't done it ...' Like that, like you talk with a friend." Open one's heart wide to God and get to know him better, he said. Prayer is a grace, and the Holy Spirit is present; it changes and reinvigorates one's heart so people can strike back out on their life journey.