What is meant by "ingratitude to the spouse" (kufran al-asheeri) in the Prophetic Hadith, and does it include denying a favor at a moment of anger or without reason? And is a woman who says to her husband, "I have never seen any good from you," in a moment of anger, considered to be among the people of Hellfire?

The 'ashir' (companion) in the hadith (definition) refers to the husband, and ingratitude towards him means denying his favors and not showing gratitude for them. Women were singled out for this censure because it occurs frequently among them. Righteous women are not included in this censure. This warning is general, encompassing the denial of favors and the lack of gratitude towards whoever bestows them. It is evidence that ingratitude towards rights and favors is a major sin. A woman is commanded to observe her husband's rights, to be grateful for his kindness, and not to deny his favors when angry. And whoever is not grateful to her husband, Allah will not look at her. Whoever has been ungrateful for her husband's favor should hasten to sincere repentance, for Allah accepts repentance from His servants. However, persistence in disobedience exposes one to the warning.