People who say that it is compulsory to mention God’s name while slaughtering animals, show the following verses as evidence:
“If you are believers of His evidences, eat the things which Allah’s name is mentioned.” (6:118)
“Do not eat from which Allah’s name is not mentioned as a deliberate sin. Certainly, the strayed ones incite their allies to strive against you. If you obey them, you surely become polytheists.” (6:121)
Scholars of Hanafi, Maliki and Hanbali sects understood the expression “do not eat from which Allah’s name is not mentioned” as “animals slaughtered without basmala” and built some other views based on this explanation. However, the animals which are referred as “slaughtered without the name of Allah” are nothing but the animals that polytheists sacrifice to their deities.
Allah the Almighty commands:
“Say: I cannot find in what has been revealed to me anything forbidden for anyone who wants to eat unless it is carrion, outpoured blood and the swine flesh, all of which is unclean; or that which is slaughtered in a name other than of Allah as a deliberate sin. Whoever falls into a state of necessity (and eats) without (the intention of) transgressing and without exceeding the limits (let him know that) your Lord surely forgives and shows mercy.” (6:145)
Therefore, in the light of this verse, while saying “Do not eat from which Allah’s name is not mentioned as a deliberate sin”, God actually says “Do not eat from which some other name than Allah is mentioned as a deliberate sin”.
Another thing important about 6:121 is that the verse ends with a warning of “becoming one of polytheists”. This also shows that the action mentioned in the verse is something that violates the oneness of God.
We can see an inventory of what those polytheists were doing about animals in the verse below:
“They say: These cattle and crops are untouchable (sacred). Nobody is to eat from them except whom we entitle(!), according to their claims. And there is the cattle which are forbidden to mount and there is the cattle which they do not mention Allah’s name (while slaughtering). All of these, they do by slandering Allah and Allah will punish them for their slanders.” (6:138)
The expression “the cattle which they do not mention Allah’s name (while slaughtering)” is understood by scholars such as al-Zamakhshari (d.538), Fakhr al-Din al-Razi (d.606), al-Qurtubi (d.671), al-Baidawi (d.685), al-Nasafi (d.710), Rashid Rida (d.1935), Muhammad Hamdi Yazir (d.1942) as the animals which polytheists sacrifice for their deities and deliberately mention their names rather than that of Allah.
Thus, the meaning of “cattle slaughtered without the name of Allah” in Quran is: “cattle slaughtered with some other name than Allah”.
One narration from the Messenger of God is as follows:
“Some folks came to the Messenger of God and said: Messenger of God! Some people bring us meat. We don’t know if they mentioned the name of Allah or not. Can we eat them? The Messenger of God replied: Eat them by mentioning the name of Allah”
 Alâuddin Ebî Bekr b. Mes’ud el-Kâsânî, Bedâiu’s-Sanâi’ fî Tertîbi’s-ş-Şerâi’, Beyrut, t.y., C:V, s.45-49; Muhammed Emin İbn Âbidîn, Hâşiyetü Reddi’l-Muhtâr ale’d-Dürri’l-Muhtâr, İstanbul, 1984, C:VI, s.299-302.
 Ebû Abdillah Muhammed b. Abdillah el-Haraşî, el-Haraşî alâ Muhtasari Seyyidi Halîl, Beyrut, t.y., C:III, s.15; Ebu’l-Berekât Ahmed b. Muhammed b. Ahmed ed-Derdîr, Şerhu’s-Sağîr alâ Akrebi’l-Mesâlik ilâ Mezhebi’l-İmam Malik, Beyrut, t.y., C:II, s.170.
 Ebû Muhammed Muvaffakuddin Abdullah b. Ahmed İbn Kudâme, el-Muğnî,Thk.: Abdullah b. Abdülmuhsin Türkî, Abdülfettah Muhammed el-Hulv, Kahire, 1990, C:XIII, s.289-290.
 Ebû Cafer Muhammed b. Cerîr et-Taberî, Câmiu’l-Beyân fî Te’vîli’l-Kur’an, Beyrut, 1992, C:V, s.329.
 Ebu’l-Kasım Carullah Mahmud b. Ömer ez-Zemahşeri, el-Keşşâf an Hakâiki Ğavâmidi’t-Tenzîl ve Uyûnu’l-Ekâvîl fî Vucûhi’t-Te’vîl, Thk.: Adil Ahmed Abdülmevcud, Ali Muhammed Muavvid, Riyad, 1998, C:II, s.402; Fahreddin er-Râzi, et-Tefsîru’l-Kebir, C:V, s.160; Kurtubî, el-Câmi’ li Ahkâmi’l-Kur’ân,C:VII, s.62; Ebu Said Nasırüddin Abdullah b. Ömer b. Muhammed el-Beyzâvî,Envârü’t-Tenzîl ve Esrâru’t-Te’vîl, 2 c., İstanbul, t.y., C:I, s.323; Ebu’l-Berekât Hâfızuddin Abdullah b. Ahmed b. Mahmud en-Nesefî, Medârikü’t-Tenzîl ve Hakâiku’t-Te’vîl, Beyrut, 1989, C:I, s.487; Muhammed Reşid Rıza, Tefsîru’l-Kur’âni’l-Hakîm (Tefsîru’l-Menâr), Yay. Haz., İbrahim Şemsuddin, Beyrut, 1999, C:VIII, s.110; Elmalılı Muhammed Hamdi Yazır, Hak Dini Kur’an Dili Yeni Mealli Türkçe Tefsir, İstanbul, 1936, C:III, s.2064.
 Bukhari, Tawhid, 13, Zabaih, 21; Abu Dawud, Adahi, 13-19; Nasai, Dahaya, 21; Ibn Majah, Zabaih, 4; Muwatta, Zabaih, 1.