Sheikh Fawzān said:-

As wuḍū is an act of outward purification, it is befitting to mention inward purification, with tawheed (Islamic monotheism) and repentance. These are the two greatest things with which to purify oneself; one purifies oneself outwardly with wuḍū and inwardly with tawhīd and repentance, meaning that one is ready to stand before Allāh and communicate in private with Him.

[Page 34 of Sheikh Fawzān’s Al Mulakhkhaṣ Al Fiqhī (Summary of Islamic Jurisprudence) (Arabic version)].