Unquestionably, they the disbelievers turn away their breasts to hide themselves from Him. Unquestionably, [even] when they cover themselves in their clothing, Allah knows what they conceal and what they declare. Indeed, He is Knowing of that within the breasts.
{يَثْنُونَ صُدُورَهُمْ}
They turn away from the truth and deviate from it. For whoever approaches a thing faces it with his chest, and whoever turns away from it and deviates, bends his chest away from it and folds his flank away from it.
{لِيَسْتَخْفُوا مِنْهُ}
Meaning: They intend to hide from Allah, so that He does not inform His Messenger and the believers of their turning away. The implication of "they intend" (to lead the meaning to its implication) is similar to the implication in the Almighty’s saying: {Strike the sea with your staff, and it parted} (Ash-Shu'ara: 63), meaning: "So he struck it, and it parted."
{أَلَا حِينَ يَسْتَغْشُونَ ثِيَابَهُمْ}
They increase their concealment when they cover themselves with their garments, also out of hatred for hearing the speech of Allah Almighty, like the saying of Noah, peace be upon him: {They put their fingers in their ears and covered themselves with their garments} (Nuh: 7).
{يَعْلَمُ مَا يُسِرُّونَ وَمَا يُعْلِنُونَ}
Meaning: There is no difference in His knowledge between what they conceal and what they reveal. Therefore, there is no point in their attempts to hide, for Allah is aware of their bending of their chests and their covering with their garments, and their hypocrisy is not valid before Him.
Context: It is narrated that this was revealed regarding Al-Akhnas ibn Shariq, who would show love to the Messenger of Allah (ﷺ). He had sweet speech and a good way of narrating, so the Messenger of Allah (ﷺ) enjoyed sitting and talking with him, while he concealed the opposite of what he displayed. It is also said that it was revealed regarding the hypocrites.
Readings:
It is read: (tathnawni suduruhum) and (yathnawna) from al-thani (bending), like ahlawla from al-halawah (sweetness), which is a structure of exaggeration. It is read with both ta and ya.
From Ibn Abbas: (latathnawni).
It is read: (tathnawwuna), originally tathnawnuna (tafa'wala) from al-thana', which is the soft and weak part of fodder. It means the yielding of their chests to bending, just as soft plants bend. Or, it refers to the weakness of their faith and the sickness of their hearts.
It is read: (tathna'inna) from ithna'anna (if'alla), then hamza is added, as in abya'adat (it became white) and adha'amat (it became dark).
