Is it permissible to say, "Allaah and the Prophet are sufficient for me against every oppressor and aggressor"?

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.

It is impermissible to include the Prophet, sallallaahu ‘alayhi wa sallam, with Allaah The Almighty when speaking about who is sufficient for you. Commenting on the verse (what means): {O Prophet, sufficient for you is Allaah and for whoever follows you of the believers.}[Quran 8:64], Ibn Al-Qayyim mentioned that sufficiency is an attribute that must be dedicated to Allaah The Almighty alone. This is similar to the verse (what means): {But if they intend to deceive you - then sufficient for you is Allaah. It is He who supported you with His help and with the believers.}[Quran 8:62]

In the second verse, Allaah The Almighty differentiates between sufficiency and support. He clarifies that the first belongs solely to Him, whereas the second, which is support, belongs also to him but it can be granted through His help and His believing slaves.

Moreover, Allaah The Almighty praises the monotheists who put their full trust in Him and attribute sufficiency to Him alone. This is stated in the verse (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 2:173]

They did not say, "Sufficient for us is Allaah and His Prophet". Bearing in mind that Allaah The Almighty praises them because they attributed sufficiency to Him alone, how could it be that He would tell the Prophet, sallallaahu ‘alayhi wa sallam, that He, as well as the believers, are sufficient for him. In fact, the believers provide the Prophet, sallallaahu ‘alayhi wa sallam, with support but only Allaah The Almighty is sufficient for him. 

Another example is the verse (what means): {If only they had been satisfied with what Allaah and His Messenger gave them and said, "Sufficient for us is Allaah; Allaah will give us of His bounty, and [so will] His Messenger; indeed, we are desirous toward Allaah," [it would have been better for them].}[Quran 9:59]

This verse indicates that the believers attribute sufficiency to Allaah The Almighty alone. However, they attribute the act of giving and bestowing bounty to Allaah The Almighty as well as to the Prophet, sallallaahu ‘alayhi wa sallam.

Further evidence on this is the verse (what means): {Is not Allaah sufficient for His Servant [Prophet Muhammad]?}[Quran 39:36]

Allaah Knows best.