Everyone Is In Need Of Isti'aadhah

The order to take refuge is left general and as such it does not specify one set of people from another. Moreover, the Messengers and Prophets عليهم الصلاة والسلام would also do isti'aadhah, and this further serves to prove that everybody is in need of this statement. 

Prophet Nooh عليه السلام said, 

"My Lord! I take refuge with You from asking You for anything about which I have no knowledge." (Soorah Hood, 11:47) 

for which he was honoured with two things: peace and blessings, 

"It was said, 'Nooh, descend with peace from Us and with blessings on you and on the nations that will issue from those who are with you.'"(Soorah Hood, 11:48) 

Prophet Yoosuf عليه السلام said, 

"Allaah is my refuge! He is my Lord and has been good to me where I live." (Soorah Yoosuf, 12:23) 

for which he was honoured with two things: evil and lust being averted from him, 

"That happened so that we might avert from him all evil and lust." (Soorah Yoosuf, 12:24) 

Prophet Moosaa عليه السلام said, 

"I take refuge with Allaah from being one of the ignorant!" (Sooratul-Baqarah, 2:67) 

for which he was honoured with two things: the lifting of the accusation and the bringing back to life of the dead person. He also said, 

"I have taken refuge with my Lord and your Lord against your stoning me." (Sooratud-Dukhaan, 44:20) 

"I take refuge in my Lord and your Lord from every proud man who does not have faith on the Day of Reckoning." (Soorah Ghaafir, 40:27) 

for which he was honoured with two things: the destruction of his enemy and his inheriting of their lands and homes. 

The mother of Maryam عليها السلام said, 

"I have named her Maryam and placed her and her children in Your safekeeping from the accursed Shaytaan." (Soorah Aali-'Imraan, 3:36) 

for which she was honoured with two things: 

"Her Lord accepted her with approval and made her grow in health and beauty." (Soorah Aali-'Imraan, 3:37) 

And Maryam عليها السلام said, when she saw the angel, 

"I take refuge from you with the All-Merciful." (Soorah Maryam, 19:18) 

and was honoured with two things: a son without a father (Prophet 'Eesaa [Jesus] عليه السلام), and a son who absolved her of the accusations against her while still in his cradle. 

[The Spiritual Cure, pp. 46-48]