Tafseer Ibn Kathir of AZ ZUMAR [17]

17. Those who avoid At-Taghut by not worshipping them and turn to Allah, for them are glad tidings; so announce the good news to My servants. 18. Those who listen to the Word and follow the best thereof, those are (the ones) whom Allah has guided and those are men of understanding.

(Those who avoid At-Taghut by not worshipping them) was revealed concerning Zayd bin `Amr bin Nufayl and Abu Dharr and Salman Al-Farisi, may Allah be pleased with them. The correct view is that it includes them and all others who avoided worshipping idols and turned to the worship of Ar-Rahman. These are the people for whom there is good news in this world and in the Hereafter. Then Allah says:

(so announce the good news to My servants -- those who listen to the Word and follow the best thereof,) meaning, those who understand it and act in accordance with it. This is like the Words of Allah, may He be exalted, to Musa, peace be upon him, when He gave him the Tawrah:

(Hold unto these with firmness, and enjoin your people to take the better therein) (7:145).

(those are whom Allah has guided) means, those who are described in this manner are the ones whom Allah has guided in this world and the Hereafter.

(and those are men of understanding.) means, they possess sound reasoning and an upright nature.