What is valid for an unspecific vow (Nathr) to offer a sacrificial gift (Hady)?

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If an offering (Hady) is vowed without specification, only what suffices for the legal sacrifice (Adhiya) is acceptable. This is the position held by Abu Hanifa and one of the two opinions of Al-Shafi'i. This is because an unspecified vow is understood according to the established practice of the Islamic Law (Shar').