Allah says in Surah Al-A’raf,
(201. Verily, those who have Taqwa, when an evil thought comes to them from Shaytan, they remember (Allah), and (indeed) they then see (aright).)
(202. But (as for) their brothers (the devils’ brothers) they (the devils) plunge them deeper into error, and they never stop short.)
Allah mentions His servants who have Taqwa, obeying His orders, and avoid what He forbade:
(when comes to them) an evil thought, or anger, or the whispers of Shaytan cross their mind, or intend to err, or commit an error,
(they remember) Allah’s punishment, as well as, His tremendous reward. They remember Allah’s promises and threats, then repent, go back to Him, seek refuge with Him and ask for forgiveness before death,
(and (indeed) they then see (aright)) they become aright and aware of the error of their ways.
Allah said next,
(But (as for) their brothers they plunge them deeper) in reference to the devils’ brothers among mankind. Allah said in another Ayah, (Verily, the spendthrifts are brothers of the Shayatin) (17:27) for they are followers of the Shayatin, who listen to them and obey their orders.
(They plunge them deeper into error) the devils help them commit sins, making this path easy and appealing to them
(and they never stop short) for the devils never cease inciting mankind to commit errors.
`Ali bin Abi Talhah reported that Ibn `Abbas commented on Allah’s statement,
(But (as for) their brothers they plunge them deeper into error, and they never stop short.) “Neither mankind stop short of the evil that they are doing nor the devils stop short of luring them. ” Therefore,
(they never stop short) refers to the devils getting tired or stopping their whispering.
Allah said in another Ayah,
(See you not that We have sent Shayatin against the disbelievers to push them to do evil) (19:83) persistently luring the disbelievers to commit evil, according to Ibn `Abbas and others.
Source : Tafseer Ibn Kathir, Al-A’raf, verses 201 and 202, Dar-us-Salam English Publication