It was narrated by one of the Prophet’s (May Allāh praise him and Peace be upon him) wives that he saw a man praying and a coin sized area on his foot had not been reached by water. So he told the man to repeat his wuḍū` and his prayer and said to him “Woe to the ankles because of the fire” [Ṣaḥīḥ Bukhārī (60)]

Sheikh Fawzān – may Allāh preserve him – says:

O Muslims, be informed that performing wudhhoo’ well does not mean using huge quantities of water, but it means making the water flow over all of each part of the body. Pouring the water is wasteful and prohibited. [Page 35 of Sheikh Fawzān’s Al Mulakhkhaṣ Al Fiqhī (Summary of Islamic Jurisprudence) (Arabic version)].