Does Al-Bayhaqi believe that Ibn Khuzaymah reverted to the Ash'ari school of thought, or that he only recanted a specific issue, based on Al-Bayhaqi's statement: "And Muhammad ibn Ishaq reverted to the way of the Salaf and regretted what he had said"?

Firstly, a reader of the history of Kalam thought and the Ash'ari heritage will find that some of them distinguish between the doctrine and method of the Salaf. They may agree with the Salaf or disagree with them, contrary to the assumption that they mean by the method of the Salaf, the Ash'ari method.

Secondly, what Al-Bayhaqi mentioned about Ibn Khuzaymah's return to the method of the Salaf, perhaps he meant his abandonment of delving into matters of Kalam. Sheikh al-Islam Ibn Taymiyyah sees that people were divided between supporters and opponents of Ibn Khuzaymah after this issue. In any case, there is no transmission from Ibn Khuzaymah proving his retraction from a specific matter, nor did Al-Bayhaqi himself claim that. And even if we concede that he retracted from something of "Kalam," his book "Kitab Al-Tawhid" is not of this genre. What is important here are two matters:

First: If it were proven that Imam Ibn Khuzaymah engaged in some Kalam and then retracted from it, his book "Kitab Al-Tawhid" is not among what is said he retracted from. Rather, he authored it to affirm the Sunnah and refute innovation.

Second: A disagreement arose between Ibn Khuzaymah and some of his students due to their influence by Ash'ari Kalam. Ibn Khuzaymah admonished them due to their inclination towards the Kullabiyyah (Ash'ariyyah), and the matter continued even after his death.