The following extract states the occasion when the wearing of phylacteries was prescribed as an equivalent that would be accepted instead of the observance of the law: — " Rabbi Eliezer said the Israelites complained before God one day, ( We are anxious to be occupied day and night in the law, but we have not the necessary leisured Then the Holy One — blessed be He! — said to them, Perform the commandment of the phylacteries, and I will count it as if you were occupied day and night in the law. ' ( Yalhut Shimeoni.) Phylacteries, fringes, and Mezuzah, these three preserve one from sin; as it is said (Eccl. iv. 2)," A threefold cord is not quickly broken; as also in Ps. xxxiv. 7, " The angel of the Lord encampeth about them that fear Him, and delivereth them." Ibid.% fol. 43, col. 2.
Why Wearing Tefillin Counts as Studying Torah Day and Night
Menachot 43b; Yalkut Shimoni