Is what happened between the man and the woman considered adultery that necessitates the prescribed punishment (hadd), and is sincere repentance sufficient for it?

The sexual intercourse that establishes zina (unlawful sexual intercourse) necessitating the hadd (prescribed punishment) is the complete insertion of the glans into the woman's vagina. The establishment of the hadd is entrusted to the ruler. However, if the matter does not reach the ruler, then the Muslim must conceal their act and strive to achieve repentance, as the Messenger of Allah, peace and blessings be upon him, said: "Whoever commits any of these abominable acts, let him conceal himself with Allah's concealment." If the matter does not reach actual zina that necessitates the hadd, it is still a reprehensible sin of figurative zina, as the Prophet, peace and blessings be upon him, called it: "The zina of the eyes is looking, the zina of the ears is listening, the zina of the tongue is speaking, the zina of the hand is striking, the zina of the foot is stepping, and the heart yearns and wishes, and the private part confirms or denies that." Whoever falls into that must repent to Allah Almighty and conceal their act. True repentance involves abandoning the sin, regretting having committed it, and resolving not to return to it, and it erases what came before it.