وَلَوْ تَقَوَّلَ عَلَيْنَا بَعْضَ الْأَقَاوِيلِ ﴿44﴾ لَأَخَذْنَا مِنْهُ بِالْيَمِينِ ﴿45﴾ ثُمَّ لَقَطَعْنَا مِنْهُ الْوَتِينَ ﴿46﴾
And had he forged some statements in Our name, We would have certainly seized him by the right hand, and then severed his life-astery,…(69:44-46)
The word taqawwul means 'to forge, fabricate or concoct' and the word watin refers to 'aorta or life-artery'. This is the main artery that carries blood from the heart to other parts of the body. Once this artery is cut off, death occurs instantly.
The foregoing verses refute the outrageous thoughts of the disbelievers. They used to accuse the Prophet o ﷺ of being a poet and a soothsayer. They said that the Qur'an was the word of a poet or the word of a soothsayer. The Qur'an denounces their argument - it is not the word of a poet nor the word of a soothsayer; it is a revelation from Allah to His Messenger ﷺ . In other words, in verses [ 37-38] it was claimed that all visible and invisible things prove that the Prophet is Allah's true Messenger and that the Qur'an is Allah's revealed Word and not the imaginary flight of a poet's mind or the wild conjectures of a diviner. In this and the preceding three verses another invincible argument is given in support of his claim. The argument is to the effect that if the Prophet ﷺ had been a forger of lies against Allah, Allah's strong hand would have seized him by the throat and cut off his life-artery and he would have certainly met with a violent death. The invincible argument is put forward in a strong language - assuming the impossible - to make the ignorant realise the worst-case scenario. The expression 'right hand' is used probably because when a convicted criminal is to be executed, the executioner stands in front facing the condemned person. The executioner's left hand faces the guilty person's right hand. The executioner holds the condemned person with his left hand and attacks him with his right hand.
A Cautionary Note
This verse refers to a theoretical situation relating to the Apostle of Allah in particular that lest, God forbid, if he were to concoct a word and impute it to Allah, this is the way he would have been dealt with. A hypothetical situation is a possible situation, not an actual situation. Thus this does not necessarily set down a universal principle that any and every impostor, who lays claim to prophethood, would be destroyed as a matter of general rule. History records that many impostors laid claim to prophethood, but no such destructive punishment was ever imposed on them.