Say, "Sufficient is Allāh between me and you as Witness. He knows what is in the heavens and earth. And they who have believed in falsehood and disbelieved in Allāh - it is those who are the losers."
Allah tells us how the idolators stubbornly demanded signs, meaning that they wanted signs to show them that Muhammad was indeed the Messenger of Allah ﷺ, just as Salih was given the sign of the she-camel. Allah says:
قُلْ
(Say) -- `O Muhammad' --
إِنَّمَا الاٌّيَـتُ عِندَ اللَّهِ
(The signs are only with Allah) meaning, `the matter rests with Allah, and if He knew that you would be guided, He would respond to your request, because it is very easy for Him to do that. Yet He knows that you are merely being stubborn and putting me to the test, so He will not respond to you.' This is like the Ayah,
The status of the narrations of the People of the Book quoted by the commentators in their commentaries is also the same. The object of their reproduction in the commentaries is meant to highlight their historical position. They cannot be used for determining what is permitted (halal) and what is not permitted حَرَام (haram).
مَا كُنتَ تَتْلُو مِن قَبْلِهِ مِن كِتَابٍ وَلَا تَخُطُّهُ بِيَمِينِكَ إِذًا لَّارْتَابَ الْمُبْطِلُونَ (And you have never been reciting any book before this, nor have you been writing it with your right hand, had it been so, the people of falsehood would have raised doubts. - 29:48). That is Before the revelation of the Qur'an you could neither read nor write, rather you were unlettered (اُمِّی). If it was not so, and you were literate, then there could have been a possibility of doubt for the infidels to put the blame that you were repeating what you had read in, the earlier books, Torah and Injil, and it was not a new revelation sent down on you by way of prophethood.'
People used to raise the objection that the Prophet Muhammad had not been given signs of God such as had been given to others, such as Moses, God’s answer to them was that signs or miracles were matters pertaining to Him and not to the prophets. The real support of the Prophet’s call of Truth are the sound arguments. Owing to certain considerations, God sometimes does give His signs or miracles to a prophet, but sometimes He does not. Faith is a conscious experience. Faith finds its place in a man’s heart once he is convinced by arguments in its favour. One who accepts something after testing it in the light of arguments is a protagonist of Truth, and one who indulges in irrelevant discussions is a worshipper of falsehood.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.