THE CONDITIONS FOR SHORTENING THE PRAYER
f15.8 The conditions for shortening the prayer while travelling are:
(a) (O: that the trip be legitimate (def: f15.5);
(b) that it be at least 81 km./50 mi. one way;
(c) that the destination be known (f15.4));
(d) that the prayer take place from start to finish while on the trip (A: if one's vehicle arrives before the prayer is finished, one prays the full number);
(e) that the intention to shorten the prayer coincide with the opening Allahu Akbar (O: it not being valid if made after this);
(f) that no portion of the prayer be performed while following an imam who is praying the full number of rak'as;
(g) (O: that one be aware of the permissibility of shortening prayers for travel;
(h) and that the intention be free of things which nullify it (A: such as vacillation or doubts (dis:below)).One must pray the full number of rak`as if:
(1) (non-(d) above) the intention to stay at the place for 4 days occurs during the prayer;
(2) (non-(h)) one is uncertain whether one's intention was to shorten, but one soon recalls that one did intend it;
(3) (non-(h)) one vacilates in the intention between shortening the prayer or not doing so;
(4) or (non-(f)) one does not know whether one's imam is shortening or not, though if one does not know the imam's intention, it is valid to intend that if the imam shortens the prayer, one will shorten, and if he prays the full number, one will pray the full number, and then to do this
