Mark 10:38-40

38And Jesus said to them, Ye do not know what ye ask. Are ye able to drink the cup which I drink, or be baptised with the baptism that I am baptised with?

39And they said to him, We are able. And Jesus said to them, The cup that I drink ye will drink and with the baptism that I am baptised with ye will be baptised,

40but to sit on my right hand or on my left is not mine to give, but for those for whom it is prepared.