Musannaf Ibn Abi Shaybah

Hasan (may Allah have mercy on him) said: It is not permissible for a Muslim to send (sell) food or weapons to the enemies, by which they gain strength against the Muslims; whoever does so is a transgressor (fasiq).

Hazrat Ata (may Allah have mercy on him) disliked selling weapons to the enemy. The narrator says: I asked, "How about selling horses?" He also forbade that, and said: Do not sell anything by which they gain strength in war; there is no harm in selling other things.

Hazrat Umar bin Abdul Aziz (may Allah have mercy on him) forbade the sale of horses towards the land of Hind.

Hasan (may Allah have mercy on him) disliked taking weapons or horses to the enemy's land for trade.

Ibrahim also disliked carrying weapons and any profitable items.

Hasan (may Allah have mercy on him) and Ibn Sirin (may Allah have mercy on him) disliked the sale of weapons during days of war.

It is narrated in the same way from Hasan (may Allah have mercy on him) and Hazrat Ibn Sirin (may Allah have mercy on him).

Hasan (may Allah have mercy on him) said: Weapons or horses will not be sent to the people at war, nor will help be sought with weapons and horses.