1. Ahmad ibn Idris has narrated from al-Hassan ibn Ali al-Kufiy from ‘Ubays ibn Hisham from Aban ibn ‘Uthman from ‘Abd al- Rahman who has said the following: “I once asked abu ‘Abd Allah عليه السلام, about a man who was captured by the Romans, and he did not fast in the month of Ramadan because he did not know which month was it. He (the Imam) said, ‘He is required to fast for one month. He then tries to calculate; if the month that he has fasted is before the month of Ramadan; it is not sufficient, and if it is after the month of Ramadan, it is then sufficient.’”