In our Lord’s time the Jews had adopted the Greek and Roman
division of the night into four watches, each consisting of
three hours, the first beginning at six o’clock in the evening
(Luke 12:38; Matt. 14:25; Mark 6:48). But the ancient division,
known as the first and second cock-crowing, was still retained.
The cock usually crows several times soon after midnight (this
is the first crowing), and again at the dawn of day (and this is
the second crowing). Mark mentions (14:30) the two
cock-crowings. Matthew (26:34) alludes to that only which was
emphatically the cock-crowing, viz, the second.