Is saying, "And repentance, I will not do such and such," considered an oath, and is expiation required if the speaker breaks it?

If the intent behind swearing by "repentance" (التوبة) is the act itself, then this oath is not binding if sworn by other than Allah, and no expiation is due for it, based on the Prophet's (peace and blessings be upon him) saying: "Whoever is to swear an oath, let him swear by Allah or remain silent." This type of oath is disliked. However, if the intent is to swear by Surat At-Tawbah (the chapter of repentance), then this is a binding oath for which expiation is due upon breaking it, because it is an oath by the Word of Allah, which is one of His attributes.