Shafaqna (Shia International News Association) – The Grand Ayatollah Sistani answered some questions regarding Qasr Prayers. According to Shafaqna the questions and answers are as follows:
Question 1: Who is a Kasir al-Safar (frequent traveler)?
Answer: One who travels for ten days in a month and sixty days in six months, he is considered a frequent traveler. Therefore, he should offer complete prayers and observe fast.
Question 2: If a person intends to commit a sin during his journey and he moves out with such an intention, does he need to offer his prayer as qasr?
Answer: If a person has journeyed to commit a sin, he should, on his return, shorten his prayers, if the return journey alone covers 8 farsakh. And the recommended precaution is that if he has not done Tawba, he should offer qasr as well as full prayers.
Question 3: Is it necessary for a hunter who goes out hunting to shorten his prayer?
Answer: If a person goes out for hunting, with the object of sport and pleasure, his prayers during the outward journey will be full, and on return it will be qasr if it does not involve hunting. But if a person goes out for hunting, to earn his livelihood, he should offer shortened prayers. Similarly, if he goes for business and increase in his wealth, he will pray qasr, although in this case, the precaution is that he should offer qasr as well as full prayers.
Question 4: When should one say his salat full (tamam) and when should one say it qasr (two rakat instead of four)? Is the general perception about a person being resident of a city sufficient for him to say his salat fully [in that city]?
Answer: he conditions for qasr in travelling have been mentioned in the Manual of Islamic Laws. When a person considers residing in a city for a long time, and in the general perception it is considered as such, he is not considered as a traveller (e.g., if he intends to reside in that city for year and a half, it will be considered as his home-town after one month). But if he intends to stay in that city for a short while only and is considered, in the general sense, as a visitor, he should pray qasr.
Source: Ayatollah Sistani