The Messenger of Allah's ﷺ oath used to be, "No, and I seek Allah's forgiveness."
حدثنا أبو بكر بن أبي شيبة حدثنا حماد بن خالد ح و حدثنا يعقوب بن حميد بن كاسب حدثنا معن بن عيسى جميعا عن محمد بن هلال عن أبيه
كانت يمين رسول الله ﷺ لا وأستغفر الله
No references are available.
Its isnad is daif. Abu Dawud transmitted it in "The Book of Oaths and Vows," chapter "What Has Been Said About the Nature of the Prophet's ﷺ Oath," Hadith 3265, from the hadith of Muhammad bin Hilal, from him. I say, Hilal is obscure, no one but Ibn Hibban has vouched for his reliability, and Allah knows best.