Mark 2:18-19

18 At this time, the disciples of John the Baptist and the disciples of the Pharisees were fasting. Some people came to Jesus and they asked him this question: ‘The disciples of John and the disciples of the Pharisees often fast for a time. So why do your disciples never do that?’

2:18John the Baptist and the Pharisees taught their disciples to fast (stop eating food) for a certain time. They did this to show that they were serving God.

19 Jesus answered them, ‘When a man marries, his friends cannot refuse to eat. They cannot fast while he is with them.