After previously affirming the oneness of Allah, we then go on to testify the second part of the complete شهادة by saying وأشهد أن محمدا عبده ورسوله usually translated as, “and I testify that Muhammad is His slave and messenger.”
It is pertinent to note that while the same meaning could have been conveyed without repetition of the word أشهد, the repetition serves to reinforce and remind us of the importance of this testimony in itself, to indicate that our faith cannot be complete without this part of the testimony.
This point is further reinforced by employing أنَّ - a more emphatic form of أن which was observed in the initial segment of the شهادة. This is done to ensure that this section stands on par with the first, which emphasised its point by incorporating the لا of absolute negation in لا إله.
We refer to Muhammad (peace be upon him) as a عبد - a slave - to remind ourselves that he is a human like us, albeit the best human to ever walk the face of the earth, endowed with unsurpassable moral character. And that if he (peace be upon him) is a humbled slave of Allah, His property, then what place does arrogance and ego have within our own selves?
We also describe him as a رسول of Allah, signifying someone who conveys a message from a supreme authority. In adopting this term, we achieve a comprehensive portrayal of him, as earlier in the tashahhud we referred to him (peace be upon him) as a نبي, and now as a رسول. The former term underscores his function in relation to the people, while the latter accentuates his function in relation to Allah.
So when we say وأشهد أن محمدا عبده ورسوله we are essentially saying, “And I have firmly concluded through my insight and observation of the signs around me, and can therefore testify, that Muhammad is certainly both a humbled slave of Allaah, and also that he is distinguished by receiving revelation, having conveyed to us a message from Allah, the Most High.