When was the practice of using the intercalary month discontinued in the life of the Prophet? And was its use discontinued since the Farewell Sermon, meaning in the new Hijri year following the year of the Farewell?

The Farewell Pilgrimage of the Prophet, peace and blessings be upon him, in the tenth year of the Hijra, coincided with the return of the month of Dhul-Hijjah to its original position. This was after the people of Jahiliyyah (pre-Islamic ignorance) used to alter the order of the months by declaring them lawful or unlawful, and by advancing or delaying them, a practice known as An-Nasi' (postponement). The Prophet, peace and blessings be upon him, had performed several pilgrimages in Mecca before the Hijra, and he never abandoned the Hajj while he was in Mecca.