Tafsir of Al-Hajj 22:69

"Allah will judge between you." This is a consolation to him—may Allah bless him and grant him peace—and the address is general, directed toward both parties, the believers and the disbelievers. It is not specific to the disbelievers, as was the case in the preceding passage, nor is it included within the scope of the speech [of the disbelievers]. It has also been suggested that it is included [in their speech] by way of dominance (taghlib). That is, Allah will adjudicate between the believers among you and the disbelievers on the Day of Resurrection through reward and punishment, just as He adjudicated in this world by establishing the proofs of the truthful over the falsifier.

"Regarding that wherein you used to differ."

That is, regarding matters of religion. It is also said: [it refers to] the disputes and the disagreement concerning the matter of sacrificial animals. The meaning of disagreement is the departure of each party toward a position different from that which the other has taken.