13. one another--Greek, "yourselves"; let each exhort himself and his neighbor.
      daily--Greek, "on each day," or "day by day."
      while it is called To-day--while the "to-day" lasts (the day of grace, Lu 4:21, before the coming of the day of glory and judgment at Christ's coming, Heb 10:25, 37). To-morrow is the day when idle men work, and fools repent. To-morrow is Satan's to-day; he cares not what good resolutions you form, if only you fix them for to-morrow.
      lest . . . of you--The "you" is emphatic, as distinguished from "your fathers" (Heb 3:9). "That from among you no one (so the Greek order is in some of the oldest manuscripts) be hardened" (Heb 3:8).
      deceitfulness--causing you to "err in your heart."
      sin--unbelief.

JFB.