'Harden Your Hearts' in the Bible

Wherefore then do ye harden your hearts, as the Egyptians and Pharaoh hardened their hearts? when he had wrought wonderfully among them, did they not let the people go, and they departed?

Do not harden your hearts as at Meribah,as on that day at Massah in the wilderness

ye may not harden your hearts, as in the provocation, in the day of the 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 doth limit a certain day, 'To-day,' (in David saying, after so long a time,) as it hath been said, 'To-day, if His voice ye may hear, ye may not harden your hearts,'