Adam Clarke on John 11:19

Many of the Jews came - Bethany being so nigh to Jerusalem, many of the relatives and friends of the family came, according to the Jewish custom, to mourn with the afflicted sisters. Mourning, among the Jews, lasted about thirty days: the three first days were termed days of weeping: then followed seven of lamentation. During the three days, the mourner did no servile work; and, if any one saluted him, he did not return the salutation. During the seven days, he did no servile work, except in private - lay with his bed on the floor - did not put on his sandals - did not wash nor anoint himself - had his head covered - and neither read in the law, the Mishnah, nor the Talmud. All the thirty days he continued unshaven, wore no white or new clothes, and did not sew up the rents which he had made in his garments. See Lightfoot, and see on Joh 11:31 (note).