Is expiation obligatory for one who swears by the Prophet falsely, knowing that swearing by other than Allah is not permissible?

Swearing by other than Allah is prohibited and does not constitute a valid oath, nor does it entail expiation according to the majority of scholars, such as Malik, Abu Hanifa, Shafi'i, and Ahmad in one of the two narrations. They cited as evidence the hadith: "Whoever swears an oath, let him swear by Allah or remain silent," and "Whoever swears by other than Allah has disbelieved or committed shirk." As for one who falsely swears by the Prophet, he must repent. Expiation is only obligatory for a binding oath.