When to Shorten Prayers During Travel
Question
Is there a distance to travel after which a person would be considered a traveller, such as seventy or something kilometers from your home (what I have heard) and then the prayer can be shortened? If you are at work, are you considered a traveller? Or is prayer easy on you during travel if and only if you are travelling for the cause of God and not work, visiting relatives, going on a picnic, shopping etc?
Response
There is a difference of opinion amongst scholars regarding the distance travelled before shortening one's prayer. More than that, some scholars have also argued that unconditionally shortening prayers during travel is perhaps not the very best option. The reason for this is the following verse from the Quran:
In this particular verse, the permission to shorten the prayer has been given in the case where believers used to fear that their enemies may attack them. Prophet Muhammad (pbuh), as reported in some of his narrations, extended this provision to the times of peace too. The best opinion, it seems, is that one may shorten the prayer if they are in a state of mind that causes them some sort of fear, anxiety or other psychological or physical difficulty due to the circumstances. For instance, if one is in a state where they are worried about getting delayed or missing their bus, train, plane etc, they may shorten their prayers so they can offer it with full concentration, yet helping them with their worry. The reason for the travel can be anything.
Other opinions include defining the number of days of travel (such as 4, 10, 19 or 20) which to me is closer in spirit than the distance to travel both because as mode of trasportation changes, the ease in travel changes and because the narrations attributed to the Prophet (pbuh) also seem to suggest the measurement to be based on the time it took for a given journey. However, I prefer the first opinion discussed earlier in this response because it is more inline with the spirit of Quranic commandment.
I would say that you should look at the meaning of the word 'traveller' or 'journey' outside the scope of a prayer first and then judge it. For instance, if you go to your work, do you think, in general, that you 'travel' or undergo a 'journey'? If you believe you do, then perhaps it falls in that category. It depends on how far your work is from your home and how much difficulty does it pose.
Even though the original leave of shortened prayers was in the circumstances of war, shortened prayers can be offered when you are travelling for other reasons as well. The purpose of the travel does not make a difference; the Prophet (pbuh) seems to have clarified this issue in some of his narratives. So whether you are travelling for a religious cause, shopping, visiting relatives, picnic, you can offer shortened prayers once you have established that you need to offer shortened prayers due to the circumstances.
