7797. 'And Jehovah made Pharaoh's heart unyielding' means that they remained obstinate. This is clear from the meaning of 'making the heart unyielding' as remaining obstinate, dealt with in 7272, 7300, 7305. The fact that Jehovah does not make the heart unyielding or do anything bad, even though it is attributed to Him in the literal sense of the Word, see 7533, 7631, 7643.
Arcana Coelestia # 7305
7305. 'Pharaoh's heart is inflexible; he refuses to send the people away' means that they were obstinately determined not to leave those whom they were molesting. This is clear from the meaning of 'heart is inflexible', also 'unyielding' and 'hardened', as obstinacy, as above in 7272, 7300; from the meaning of 'refusing to send away' as not leaving; and from the representation of 'Pharaoh', about whom these things are said, as those who engage in molestation, dealt with previously.