How can the differing narrations regarding a dog licking a vessel be reconciled, such as the necessity of washing, seven washings, and rubbing the eighth with earth, along with an explanation of the scholars' opinions and the most preponderant among them?

The vessel licked by a dog must be washed seven times, one of them with earth. Narrations differ regarding which of the washings should be with earth: the first, the last, one of them, the seventh, or the eighth. The preponderant view is that the earth should be used in the first washing, or that there is an option in the matter. It is also possible that the differing narrations resulted from a doubt on the part of some narrators. The schools of thought have differed on adopting this ruling; the Shafi'is have adopted it, while the Hanafis and Malikis have differed on the matter.