In this research, there is a study and investigation of the worship of fasting from the book "YNabi` al-Ulum" by the scholar Shams al-Din Ahmad ibn al-Khalil al-Khoei (d.637AH), which contained a number of sciences, including the science of the jurisprudence of worship, and he walked in it in a very creative and orderly way, so he dealt with the worship of fasting by exposing seven Issues, followe...