Mālik stated this explicitly (1).

Imam Ahmad and Abū Ḥanīfah said, “Nard is more strictly forbidden than chess.”

Shaykh al-Islām Abū al-ʿAbbās Ibn ʿAbd al-Ḥalīm Ibn ʿAbd al-Salām al-Ḥarrānī, may Allah have mercy on him, explained: “Both views are correct from different angles. In most cases nard is played for stakes, unlike chess; therefore nard with stakes is worse than chess when chess is free of stakes. However, if both games involve stakes, or both are free of them, then chess is worse than nard, because it demands a level of concentration that distracts the player far more than nard does. For this reason it is said that chess rests on the doctrine of qadar (human choice), whereas nard rests on jabr (determinism) (2). Its harm to both intellect and religion is therefore greater than that of nard. When no stakes are involved, the prohibition concerns the act itself; when stakes are present, the prohibition comes from two sides—the act and the unlawful consumption of wealth—making it akin to eating the flesh of carrion swine.

Ahmad said, “It is forbidden on two counts, and if someone were to seize or steal it from a Christian, it would be forbidden on three.”

Thus the degree of prohibition waxes and wanes in proportion to the strength or weakness of the associated harms, and in proportion to