To what extent is the fatwa permitting usurious transactions with a warring infidel, attributed to Abu Hanifa and his student Muhammad ibn al-Hasan, authentic?

Usury (riba) is one of the gravest sins. Allah has warned those who deal in usury that their wealth will be obliterated and that they will suffer a severe torment. The prohibition of usury is explicit in the Quran and Sunnah, and it is not permissible to circumvent it by changing its name. What is attributed to Abu Hanifa regarding the permissibility of usury in Dar al-Harb (land of war) is a fabrication against him and contradicts his actual statements. His conditions for the permissibility of such dealings were that the contract must be in Dar al-Harb, that the land must genuinely be "Dar al-Harb," and that the Muslim must be the recipient of the usury, not the giver. The correct view is that usury is forbidden between a Muslim and another Muslim, and between a Muslim and a non-believer, in every place and time. This is the opinion of the majority of scholars. As for the evidence cited by some for the permissibility of usury in Dar al-Harb, it is weak in terms of its chain of narration (sanad) and its inferential reasoning. A mursal hadith (one with a missing link in the chain) is not to be used as proof. The hadith about Banu Qaynuqa and Banu al-Nadir is weak. The story of the Prophet wrestling Rukana and Abu Bakr's wager with the polytheists of Quraysh is either abrogated or permissible because it relates to supporting the religion. As for Al-Abbas's usury, it occurred before his conversion to Islam. And their argument that the wealth of non-believers is permissible is invalid if a Muslim enters their land under a covenant of peace.