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 would also do istiadhah and this further serves to prove that everybody is in need of this statement.
Nuh, peace be upon him, said, “My Lord! I take refuge with You from asking You for anything about which I have no knowledge.” (Hud 11:47) for which he was honoured with two things, peace and blessings: “It was said, ‘Nuh descend with peace from Us and with blessings on you and on that nations that will issue from those who are with you…” (Hud 11:48)
Yusuf, peace be upon him, said, “Allah is my refuge! He is my lord and has been good to me where I live.” (Yusuf 12:23) for which he was honoured with two things, evil and lust being averted from him: “That happened so we might avert from him all evil and lust” (Yusuf 12:24)
Musa, peace be upon him, said, “I take refuge with Allah from being one of the ignorant.” (al-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 stoning me.” (ad-Dukhan 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.” (Ghafir 40:27) for which he was honoured with two things, the destruction of his enemy and his inheriting their lands and homes.
The mother of Maryam said, “I have named her Maryam and placed her and her children in Your safekeeping from the accursed Shaytan.” (Ali Imran 3:36) for which she was honoured with two things: “Her Lord accepted her with approval and made her grow in health and beauty.” (Ali Imran 3:37)
Maryam, when she saw the Angel, said, “I take refuge from you with the All-Merciful.” (Maryam 19:18) and was honoured with two things: a son without a father, and a son who absolved her of the accusation against her while still in his cradle. (ar-Razi, vol 1, p77)
The Spiritual Cure: An Explanation of Surah Al-Fatihah prepared and translated by Abu Rumaysah Pages 46-48