What day of the week one can observe the black fast?

Question:

Please, tell me what day of the week it is good to perform a total fast, and if this has any importance. Thank you.

There is no commandment in the Bible that God would say that one should fast a certain day of the week. The black fast is observed when you have a certain reason, a great need, when someone is sick or has any other need, when you want to cry to God and your prayer be heard above.

Translated by Felicia Rotaru