ßÊÇÈ ÇáäßÇÍ : Hadeeth No:4803 : Ibn 'Umar:
The Prophet decreed that one should not try to cancel a bargain
already agreed upon between some other persons (by offering a bigger
price). And a man should not ask for the hand of a girl who is already
engaged to his Muslim brother, unless the first suitor gives her up,
...