The Messenger, may God bless him and grant him peace, stayed in the desert of Bani Saad
The answer is: four years.
The Messenger, may God bless him and grant him peace, remained in the desert of Bani Saad for four years. During this time, he was able to learn and grow in knowledge and understanding. Bani Sa'd was a place of learning where the Prophet was able to learn about the faith and develop his understanding of God. The Prophet’s stay in the Bani Saad desert was a blessing and he was able to gain a lot from his experience. His time at Beni Saad allowed him to develop and grow spiritually, providing him with insight and understanding that helped him spread his message of peace and love. We thank the Prophet for his stay in the Bani Saad desert, because it provided us with an incomparable source of knowledge and understanding. Peace be upon him.