Abbas - Tanwîr al-Miqbâs min Tafsîr Ibn ‘Abbâs
(And when it is said unto them) to the Arab idolaters: (Follow that which Allah hath revealed) follow the lawfulness exposited by Allah concerning what is cultivated and the cattle raised, (they say: We follow that wherein we found our fathers) regarding their unlawfulness. (What! Even though their fathers were wholly unintelligent) with regard to Religion (and had no guidance) to the practice of any prophet, so how could you follow them? It is also said that this means: if their fathers did not understand about things in this world and did not follow the practice of any prophet, then how could you follow them? It is also said that this means: even though their fathers did not understand anything of Religion and were not guided to the practice of any prophet, how could they follow them?
And when it is said to them, the disbelievers, ‘Follow what God has revealed’, pertaining to affirmation of God’s Oneness and the good things that He has made lawful, they say, ‘No; but we follow what we found our fathers doing’, in the way of idol-worship, deeming unlawful the camel let loose, and [practising] the slitting of the camel’s ear (sc. bahīra). God says: What? (the hamza [of a-wa-law] is for repudiation), do they follow them, Even if their fathers do not understand anything, concerning religion, and they were not guided?, to the truth.
And when it is said to them, 'Follow what God has revealed', in terms of taking into consideration the limits of moderation and fairness in all things in the manner prescribed by the Law, they say, 'No; but we follow what we found our fathers doing', in the way of reprehensible acts of immoderation that belong to the age of ignorance, in [blind] imitation of them. Whatḍ, will you follow themḍ Even if their fathers do not understand anything, of religion or knowledge, and they were not guidedḍ, to right deeds because of their ignorance.
Allah states that if the disbelievers and polytheists are called to follow what Allah has revealed to His Messenger and abandon the practices of misguidance and ignorance that they indulge in, they will say, "Rather. We shall follow what we found our fathers following,'' meaning, worshipping the idols and the false deities. Allah criticized their reasoning:
أَوَلَوْ كَانَ ءَابَاؤُهُمْ
((Would they do that!) even though their fathers), meaning, those whom they follow and whose practices they imitate, and:
لاَ يَعْقِلُونَ شَيْئًا وَلاَ يَهْتَدُونَ
(...did not understand anything nor were they guided) meaning, they had no sound understanding or guidance. Ibn Ishaq reported that Ibn `Abbas said that this was revealed about a group of Jews whom Allah's Messenger called to Islam, but they refused, saying, "Rather, we shall follow what we found our forefathers following.'' So Allah revealed this Ayah (2:170) above."
The Disbeliever is just like an Animal
Allah then made a parable of the disbelievers, just as He said in another Ayah:
(For those who believe not in the Hereafter is an evil description.) (16:60)
Similarly, Allah said here (2:171 above)
وَمَثَلُ الَّذِينَ كَفَرُواْ
(And the example of those who disbelieve...) meaning, in their injustice, misguidance and ignorance, they are just like wandering animals, not understanding what they are told; if the shepherd heralds them or calls them to what benefits them, they would not understand what is actually being said to them, for they only hear unintelligible sounds. This is what is reported from Ibn `Abbas, Abu Al-`Aliyah, Mujahid, `Ikrimah, `Ata', Al-Hasan, Qatadah, `Ata' Al-Khurasani and Ar-Rabi` bin Anas.
صُمٌّ بُكْمٌ عُمْىٌ
(They are deaf, dumb, and blind.) means, they are deaf, as they do not hear the truth; mute, as they do not utter it; and blind, as they do not see or recognize its path and way.
فَهُمْ لاَ يَعْقِلُونَ
(So they do not understand.) means, they do not comprehend or understand anything.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
The only authority they have for their superstitious practices is that these have been the customs of their forefathers, and the foolish followers consider this a good authority.
This parable has two aspects:
(1) That these people are like those herds of cattle which merely hear the call and cry of the drovers and move about at the sound of their call without understanding the meaning of their words.
(2) That preaching before them is like preaching to the cattle which only hear the sounds but do not comprehend the meaning and the implication of the words that are spoken to them. The words used are comprehensive and cover both the aspects.
And when it is said to them “Follow what God has revealed” they say “No; but we follow what we found our fathers doing.” Whatḍ Even if their fathers do not understand anything and they were not guidedḍ There is no raising their eyes beyond that which is like them in form class kind and ancestry for they are set on their way. Without a doubt they have plunged into the fire on their path. Had they known that their ancestors had no intelligence to restrain them nor guidance to unite them they would have withdrawn from them [understanding them to be] hostile and resisted them [understanding them to be] oppositional [to God's command]. But the lights of insight were snatched from them and they were deprived of the proofs of certainty.