“I once asked abu ‘Abd Allah (a.s.), about a man who decides to fast, then he meets his brother who believes as he does; if he can discontinue his fast. He (the Imam) said, ‘If it is optional it will be counted as one day of fasting in his favor, but if it is obligatory Qada’ (compensatory fast), he must do its Qada’ (compensatory fast).”’