الكافي- ط الاسلامية, volume 4, page 141

2. A number of our people have narrated from Ahmad ibn Muhammad from Ali ibn Ahmad ibn ‘Ushaym who has said the following: “Al-Husayn once wrote to al-Rida’ (a.s.), saying, ‘I pray to Allah to keep my soul in service for your cause, a man had vowed to fast for certain days and fasted a few days, then he became ill and stopped fasting. Is he required to start fasting all over again or are the days that he had fasted are counted?’ He (the Imam) wrote the answer that said, ‘The days that he had fasted are also counted.’”

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.

3. Ali ibn Ibrahim has narrated from Salih ibn ‘Abdillah who has said the following: “I once asked abu al-Hassan (a.s.), saying, 'May I be sacrificed for you, it is upon me to fast for one month if my uncle is released from jail. He came out from jail and I decided to start the fast, but then someone from our companions came and I invited him for lunch, and I had lunch with him.' He (the Imam) said, ‘It is not harmful.’”

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.

4. A number of our people have narrated from Ahmad ibn Muhammad from al-Husayn ibn Sa‘id from al-Qasim ibn Muhammad from Ali ibn abu Hamzah who has said the following: “I once asked abu Ibrahim (a.s.), about a man who has made obligatory upon himself to fast one month in al-Kufah, one month in al-Madinah and one month in Makkah because of an affliction whereby he suffered. He fasted one month in al-Kufah, then he entered al-Madinah and fasted for eighteen days, but then the camel man did not stay any longer. He (the Imam) said, ‘He can fast the remaining days at home when he comes back.’”

Translation: Muhammad Sarwar·Thaqalayn link·The Arabic above is the original.