Prayer: How long must one intend to stay in a place for full prayer and valid fasting?

Practical Laws of Islam as per the teachings of Imam Khamenei

Prayer: How long must one intend to stay in a place for full prayer and valid fasting?

English:

Question #682:

Someone wants to stay in a place temporarily, how long should he intend to be there so that his prayer is full and his fast is valid?

Answer #682:

If he is to live there for one or two years at least, his prayer is full and his fast is valid.

-Imam Khamenei, Practical Laws of Islam, Importance and Conditions of Prayer