Answer
Ali ibn Husayn al-Sajjad, also known as Ali al-Sajjad, was the fourth Shia Imam and the son of Imam Husayn. He was born in Medina in 658 CE and died in 713 CE. He was known for his piety and devotion, and was given the title "al-Sajjad" (the Prostrator) because of his frequent prostrations in prayer.