'Harden' in the Bible

harden not your hearts, as in the provocation, in the day of temptation in the wilderness;

in that it is said, To-day if ye will hear his voice, do not harden your hearts, as in the provocation;

again he determines a certain day, saying, in David, 'To-day,' after so long a time; (according as it has been said before), To-day, if ye will hear his voice, harden not your hearts.