Adam Clarke's Commentary on the Bible - Genesis 4:3
In process of time - ימים מקץ mikkets yamim , at the end of days. Some think the anniversary of the creation to be here intended; it is more probable that it means the Sabbath, on which Adam and his family undoubtedly offered oblations to God, as the Divine worship was certainly instituted, and no doubt the Sabbath properly observed in that family. This worship was, in its original institution, very simple. It appears to have consisted of two parts: Thanksgiving to God as the author... read more
Adam Clarke's Commentary on the Bible - Genesis 4:2
And she again bare his brother Abel - Literally, She added to bear ( ללדת ותסף vattoseph laledeth ) his brother. From the very face of this account it appears evident that Cain and Abel were twins. In most cases where a subject of this kind is introduced in the Holy Scriptures, and the successive births of children of the same parents are noted, the acts of conceiving and bringing forth are mentioned in reference to each child; here it is not said that she conceived and brought forth... read more