Allah states that the scholars of the People of the Scripture know the truth of what Allah's Messenger was sent with, just as one of them knows his own child, which is a parable that the Arabs use to describe what is very apparent. Similarly, in a Hadith, Allah's Messenger said to a man who had a youngster with him:
"Is this your son?" He said, "Yes, O Messenger of Allah! I testify to this fact." Allah's Messenger said:
"Well, you would not transgress against him nor would he transgress against you."
According to Al-Qurtubi, it was narrated that 'Umar said to 'Abdullah bin Salam (an Israelite scholar who became a Muslim), "Do you recognize Muhammad as you recognize your own son?" He replied, "Yes, and even more. The Honest One descended from heaven on the Honest One on the earth with his (i.e., Muhammad's) description and I recognized him, although I do not know anything about his mother's story."
Allah states next that although they had knowledge and certainty in the Prophet, they still:
{conceal the truth.}

The Ayah indicates that they hide the truth from the people, about the Prophet, that they find in their Books,
{while they know it.} Allah then strengthens the resolve of His Prophet and the believers and affirms that what the Prophet came with is the truth without doubt, saying:
{(This is) the truth from your Lord. So be you not one of those who doubt.}