What it is disliked to carry to enemy land so that they gain strength from it

Al-Hasan (may Allah have mercy on him) said: It is not permissible for a Muslim to send (that is, to sell) food or weapons to the enemies, through which they gain strength against the Muslims. Whoever does this is a sinner (fasiq).

Ata (may Allah have mercy on him) used to dislike carrying weapons to the enemy. The narrator said: I said: What about carrying horses to them? He refused that as well, and said: Whatever gives them strength for fighting should not be carried to them; as for other things, there is no harm in them.

Amr bin Dinar also said the same.

Umar bin Abd al-Aziz (may Allah have mercy on him) forbade carrying horses to the land of India.

Al-Hasan (may Allah have mercy on him) used to dislike taking weapons or horses to the land of the enemy for trade.

Ibrahim also used to dislike carrying weapons or anything of benefit to the enemy of the Muslims.

Al-Hasan (may Allah have mercy on him) and Ibn Sirin (may Allah have mercy on him) used to dislike the sale of weapons in times of civil strife (fitnah).

Something similar is narrated from al-Hasan (may Allah have mercy on him) and Ibn Sirin (may Allah have mercy on him).

Al-Hasan (may Allah have mercy on him) said: Neither weapons nor horses are to be sent to the people at war, nor anything by which help is obtained for weapons and horses.

It is narrated from Qatadah that the sale of weapons during fighting used to be disliked.