Sehri and Iftaar

Finishing sehri at the last minute following an incorrect clock

Q:

1) Zaid followed his faithful bedroom clock for many years and he used to complete eating his sehri at the last minute based on the time on this clock. He recently compared his clock with the BBC time and found it to be 3 minutes slow. Is he muqallaf of following this time and repeating his fasts considering the possibilty that the BBC or any other central bureau time may also be incorrect.

Fasting without sehri

Q: My question is a night before Rajab (miraaj un nabi) I made intention of fasting keeping roza. I stayed up a little with some ibaadat so I thought I will take a hours rest an then get up for sehri but I didn't realise I fell asleep and woke up next morning. Can you please tell me if I am gunaghaar an will my fast be accepted? Can I carry on fasting during the day or not?

Changing one's niyyat before the fast commences

Q: I made a niyyat for a nafil fast about 30min before sehri ends. Just prior to sehri ending, I decided that I should rather wait and make the niyyat for keeping fast before half the day, depending on how I felt. I was not going to eat during that time, until my niyyat was confirmed. Is it ok to change my niyyat for fasting afterwards, or is the first niyyat I made 30 minutes before sehri ended binding?