Matthew 26:34

Before the cock crow] i.e. before the day begins to dawn. There is practically no difference of meaning between this and 'before the cock crow twice' (Mk), for when the cock once begins to crow in the morning, he does so at frequent intervals. The rabbis say, 'They do not keep cocks at Jerusalem on account of the holy things (which they might pollute); nor do the priests keep them throughout all the land of Israel.' But this law was clearly not enfored.