WaAAajiboo an jaahum munthirun minhum waqala alkafiroona hatha sahirun kaththab (surah Sad: 4)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(38:4) They wondered that a warner had come to them from among themselves, *4and the deniers of the Truth said: 'This is a sorcerer, *5 and a big liar.

Wa `ajibooo an jaaa`a hum munzirum minhum wa qaalal kaafiroona haazaa saahirun kazzaab

*4) That is, "They are so foolish that when a man from their own kind and from their own clan and brotherhood, whom they knew fully well, was appointed to warn them, they wondered at it, whereas it would have been strange if some other kind of creature had been sent down from heaven to warn human beings, or an utter stranger had arisen among them suddenly and started functioning as a prophet. In that case they would have been perfectly justified to say, "What an odd thing! How can this strange creature know our conditions and feelings and requirements that he should guide us? How can we test and find out the truth about the stranger who has suddenly arisen among us and know whether he is trustworthy or not? And how can we decide whether we should or should not believe in him when we have not judged and seen his character and personality?"
*5) The disblievers used the word sahir (sorcerer, magician) for the Holy Prophet in the sense that whoever came in contact with him was so influenced by him that he would become his follower like a possessed person; he would least mind severing of his connections with others or incurring material losses; the father would give up the son and the son the father; the wife would separate from the husband and the husband from the wife; he would at once be prepared to leave his country if it was so required; he would even be ready to pass through the severest persecutions for the sake of the faith. (For further details, see Surah AIAnbiya' : 3 and E. N . 5 thereof).