Should he give water to a thirsty man when he fears that he himself may become thirsty in the desert?
Question

                If a person is walking in the desert and he has some water, but he fears that he may become thirsty later on, and there is someone who is thirsty now, does he have to give him water or not?
Praise be to Allah. 
          Ibn Hajar al-Haythami was asked this question and he 
          replied: 
 
          Two views were mentioned in al-Majmoo’, in (the 
          chapter called) al-Muqaddam, and I do not know of anyone who 
          stated that one of them was more correct than the other. The one which 
          appears to be more correct is that he should give water to the one who 
          is thirsty at that time, if there is the fear that he will die of thirst, 
          because his death is certain, unlike the one who has the water, who 
          has the chance of finding more water later on. But if he is in an arid 
          land where he despairs of finding water and he thinks it most likely 
          that death is inevitable if he gives away the water that he has with 
          him, then the matter is subject to further discussion, and it is more 
          likely that giving the water in this case is not obligatory. The same 
          applies if the thirsty person fears that he may lose a limb or become 
          sick etc. because of his thirst, and the one who has the water fears 
          that he may die later on, then it is also more likely to be correct 
          that he does not have to give away the water.