What is the authenticity of the Hadith which states that whoever deliberately misses three consecutive Friday prayers will have his heart sealed by Allah with hypocrisy, and does this person remain a hypocrite until he dies, or can he repent?

Habitually neglecting the Friday prayer makes the heart rustier and diminishes one's desire for acts of obedience. Authentic hadiths attest to this. Whoever abandons it three times out of negligence will have their heart sealed. Negligence here means abandoning it without a valid excuse, and being sealed means being prevented from receiving goodness. This does not mean that Allah will not grant them repentance or accept it from them; rather, Allah accepts the repentance of whoever repents and ceases the sin. The friend should be advised to repent and show remorse, and if he repents, he should be accompanied.