Pope Francis said during a homily in Rome’s Vatican City Friday that not paying taxes, social security contributions or fair wages is a “very grave sin.” The Argentine pontiff said employers who attend church but treat their employees poorly are “using God to cover injustice,” according to Italian news agency ANSA.

“You cannot make donations to the Church on the back of the injustice that you commit with your employees," Pope Francis reportedly said in Italian at his Saint Martha residence in the Vatican. “If you go to Mass on Sunday and take communion, you should ask: what is the relationship with your employees? Do you pay them off the books? Do you pay them a fair salary? Do you pay the pension contributions?”

The pontiff’s homily comes two days after many men and women of faith attended Ash Wednesday services, during which clergy use ashes – a symbol of repentance, mourning and mortality -- to mark a cross on parishioner’s foreheads. Ash Wednesday also marked the beginning of Lent, a 40-day-long season of solemn religious observance in Christianity during which many reflect, fast and abstain from certain activities.

“As God's people today we begin the journey of Lent, a time in which we try to unite ourselves more closely to the Lord Jesus Christ, to share the mystery of His passion and resurrection,” Pope Francis said in Italian during an Ash Wednesday homily in Rome, according to Vatican Radio.

Pope Francis is no stranger to making controversial remarks. The pontiff has been praised for his shift in rhetoric on homosexuality, abortion and divorce that signals a new tone in the Catholic Church. However, he was recently criticized for comparing transgender people to nuclear weapons and genetic manipulation, according to the National Catholic Reporter.