insists
v.v. to say something very strongly and refuse to change your mind. You use this when you are sure you are right or when you demand that something happens.
v. to demand something forcefully or state a fact firmly, refusing to accept contradiction or refusal. Often followed by a 'that' clause or the preposition 'on'.
He insists that he is telling the truth.
The manager insists on seeing the original receipt before she can offer a full refund for the damaged goods.
Although the evidence against his theory was mounting, the scientist continues to insist that his initial hypothesis remains the most plausible explanation for the data.
The verb is often intransitive when followed by 'on' + gerund, or transitive when followed by a 'that' clause.
She insists to pay for dinner.She insists on paying for dinner.Insist does not take an infinitive; it requires 'on' followed by a gerund or a 'that' clause.