What is the meaning of the Hadith: "None maintains his Wudu' except a believer"? And does maintaining it mean that it is not nullified, or initiating Wudu' every time it is nullified?

The Hadith indicates that "maintaining ablution" means sustaining it as much as possible, such that a Muslim performs ablution whenever he nullifies it, even if it is not prayer time.

This is supported by what Al-Iraqi stated in "Tarh Al-Tathrib," that the Hadith indicates the desirability of perpetual purity and ablution immediately after an impurity.

Similarly, Al-Suyuti said in "Tanwir Al-Hawalik" that the Prophet's (peace and blessings be upon him) statement: "No one maintains ablution except a believer" means that a believer is one who consistently performs it in all circumstances.