After these events, King Abdul Aziz gave his orders to extend the operations carried out by his forces. Saud was by his side in Riyadh, helping him in laying the plans, observing the developments, and controlling their execution. Thus, the Saudi forces Occupied Assir to besiege Hijaz from the south, then Taif and Makkah until the King's greatest dream came true in the year (l343H/1924).
This dream is the annexation of the beating heart of the world of Islam, its kiblah, the place where the revelation occurred and the center of attention of the Muslims, which is Makkah.
King Abdul Aziz came for the first time in his life to Makkah as a pilgrim in a state of ritual consecration, leaving in Riyadh his son Saud to be in control of the state's affairs under the supervision of
his grandfather al Imam Abdul Rahman who was the object of his respect, love and esteem. Saud continued to replace his father until King Abdul Aziz occupied Jeddah. After that, the King sent his son Saud with Khaled Bin Louay holding seven flags, in the direction of (Yanbou) and its outskirts. And so, Prince Saud Annexed (what) on the 26th of Jumada II in the year [1344H/1945] He also took cannons, weapons, machine guns, aircrafts, tanks, naval ships, ammunition and supplies. After that, King Abdul Aziz conquered Medina and after he was acknowledged as King of Hijaz, his official title became "Sultan of Najd and its annexes and King of Hijaz." The ceremony whereby people swore allegiance to him was typically Islamic and it took place in the sacred city of Makkah. This ceremony was imitated in all parts of the country where the Princes in the regions represented him.
In the summer of the year (1344H-1925) Saud took permission from his father to perform his first hajj with him. According to the traditions followed during the hajj season, the(sedan chair) had to be brought from Egypt accompanied by soldiers and an Egyptian military musical band. When the procession entered Maklah a group of (hjjis) the ("fundamentalists') blocked their way and stoned them in protest against the musical band. Instead of being prudent, the Egyptian officer fired at them killing and wounding several people. Upon learning about the incident, King Abdul Aziz delegated his son Saud immediately to calm the situation before it becomes aggravated. (Saud was able to contain the violence after he had been himself exposed to fire) How as a result, Egypt adopted a negative attitude towards King Abdul Aziz by ending its relationship with him and stopping the supplies (which are fixed subventions and handouts sent annually from Egypt with the sedan chair). The relations between the two countries remained strained until the death of King Fouad and the ascent of King Faruq to the throne of Egypt in the year (l355AH-1935) when the relations became more or less better. When Saud returned to Riyadh, his father sent him to Egypt to have an eye surgery. This initiative taken by King Abdul Aziz was considered as unofficial to better the relations with Egypt after the sedan chair incident
Moreover, this visit was the first trip taken by Saud outside the country and that was in the year (1344H/1925) on board of an Egyptian ship called" al Mansoura". In Cairo, Saud met with the Egyptian Prime Minister Saad Basha Zaghlul. Thus, the meeting brought about positive results on the political front in view of strengthening the cordial relations between Saudi Arabia and Egypt.
King Abdul Aziz relied on Saud who was twenty-two years old and appointed him as his deputy in Najd, the seat of the government because he believed in his son's firm political qualifications. The King did this not because he loved his son but because he was convinced that Saud is capable of carrying such a great responsibility. In addition, the fact that he relied on him during the fight against the Sharifs in Hijaz and the fundamentalists is considered as a conclusive evidence of his trust in the qualifications and competence of his eldest son who represented him in these events. 
- ^ المختار صلاح الدين مصدر سابق ( ص . 224 ). A LETTER FROM ABDULAZIZ TO SHEIKH AHMAD AL JABIR, 1399, Archives Edition ,V.I.P 327, RULNG FAMIES OF ARABIA