All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
The saying "sufficient for me is Allaah" means that Allaah The Almighty will protect me from evil. According to the sound opinion of the scholars, ‘sufficiency’ in this sense is one of the characteristics of Allaah The Almighty. Ibn Taymiyyah considered this opinion to be the preponderant one and supported it with the verse in which Allaah The Almighty Says (what means): {If only they had been satisfied with what Allaah and His Messenger gave them and said, "Sufficient for us is Allaah…}[Quran 9: 59] Allaah The Almighty did not Say here "sufficient for us are Allaah and His Messenger" because Allaah alone is the One Who is sufficient for all His slaves, as He Says (what means): {O Prophet, sufficient for you is Allaah and for whoever follows you of the believers.}[Quran 7:64]
Accordingly, one should seek refuge with Allaah The Almighty Alone saying “Sufficient for me is Allaah” as the Companions would say. Allaah The Almighty Says about them (what means), {Those to whom hypocrites said, "Indeed, the people have gathered against you, so fear them." But it [merely] increased them in faith, and they said, "Sufficient for us is Allaah, and [He is] the best Disposer of affairs.”}[Quran 3:173]
And Allaah Knows best.