Begging is an ill trade on a fast-day.

The proverb pictures a beggar seeking help on a day when people are fasting. Those who are not eating may have little food to offer.

More broadly, it warns that a request is unlikely to succeed when the people asked cannot readily provide what is wanted. Timing matters as well as need.

Use it to comment on an ill-timed request, especially when someone seeks help or resources from people who have little to spare at that moment.