The answer is: Twice a week

Luke 18:9-14

In Luke's compelling parable of the Pharisee and the tax collector, conveyed in verses 9 through 14, we delve into two contrasting approaches to worship and piety. The Pharisee boasts about his strict fasting—twice a week! This might seem impressive, but it serves to highlight self-righteousness rather than sincere devotion. Fasting was a regular part of religious life in Ancient Israel, where it typically served to purify the spirit and foster closer communion with God. Interestingly, the Law of Moses only mandated a single fast day—on the Day of Atonement (Yom Kippur). The Pharisee's extra fasting indicates their extreme commitment, yet it's tinged with an air of smugness rather than humility.

On the flip side, the tax collector stands apart, beating his chest in remorse and uttering a simple, heartfelt plea for mercy. He acknowledges his failings with striking honesty. This demonstrates the heavenly value placed on humility, a lesson still resonant today—not the façade of perfection but genuine contrition.

Fun fact: In Judaism, self-denial during fasts isn’t about performing a ritual for recognition but rather reflects a deeper inner journey and repentance—something the tax collector exemplifies beautifully. His prayer demonstrates a profound understanding of mercy, a cornerstone of many spiritual philosophies! Lastly, this parable elegantly conveys a timeless truth—that often it's the seemingly lesser figures, in terms of societal status, who provide the profound lessons on spirituality and moral integrity.