Surah Yā-Sīn

In the name of Allah, the Most Compassionate, the Most Merciful.

As for shackles:

[Surah Yā-Sīn (36): verse 8]
“Indeed, We have placed shackles around their necks, reaching up to their chins, so their heads are forced up.” (8)

Al-Farrā’ said: “We have restrained them from spending in Allah’s cause.” Abū ‘Ubaydah said: “We have prevented them from believing by placing barriers in their way.” Since a shackle prevents the shackled person from acting and moving freely, a shackle upon the heart prevents faith.

If it is asked, “The shackle that prevents faith is in the heart, so why mention a shackle around the neck?”

The answer is that, since shackles are ordinarily placed around the neck, it was fitting to mention their customary location, although the heart is what is meant. This is like His saying, Most High: 17: 13 “And We have fastened every person’s deeds to his neck.” Hence the expressions, “My sin rests upon your neck,” and, “This rests upon your neck.” Likewise, He says: 17: 29 “And do not keep your hand shackled to your neck.” Here, withholding expenditure is likened to a hand shackled to the neck. It is in this sense that al-Farrā’ explained the words, “Indeed, We have placed shackles around their necks”: