Genesis 31:10

And it came to pass, at the time that the cattle conceived,
&c.] Whether in spring or in autumn cannot be said, for it seems this was twice a year; this probably was at the beginning of the six years' servitude, or just before the agreement was made between Laban and Jacob, and was an instruction to the latter how to make his bargain with the former: that I lifted up mine eyes, and saw in a dream;
in a vision of the night, so things were represented to his fancy and imagination: and, behold, the rams which leaped upon the cattle [were] ringstraked,
speckled, and grisled;
from whence he might conclude, that the cattle they leaped upon would bring forth the like, and so be a direction to him to make his agreement with Laban to have such for his hire; not that the rams in the flock were really of those colours, for they were all white, but so they were represented to Jacob in the vision, to suggest to him, that such would be produced by them; and it is not improbable by the artifice Jacob was directed to, and took, that the ewes, when they came to the watering troughs to drink, upon seeing the party coloured rods in the water, these made such an impression upon their imaginations, that they fancied the rams that leaped upon them were of those colours, and so conceived and brought forth the like. Here is another colour mentioned, not taken notice of before, at least by this name, "grisled"; it stands in the place of "spotted", and seems to be the same with that, and signified such as had spots on them like hailstones, and distinguishes them from the speckled: the speckled were such as were white with black spots, these such as were black, and had white spots like hail.