What is the difference between a vow (nadhr), a covenant ('ahd), and repentance (tawbah) from sin?

Abandoning sins is a religious obligation. A vow to abandon them is not binding according to the majority of scholars, and thus requires no expiation. However, Sheikh al-Islam Ibn Taymiyyah holds that it necessitates an expiation for a broken oath, and this is more cautious. Whoever makes a covenant with Allah to abandon a sin and then commits it, must offer an expiation for a broken oath along with repentance. Repentance is a spiritual act that includes abstaining from the sin, regretting it, and resolving not to return to it. Breaking repentance only necessitates renewing it and being sincere in it.