'The Messenger of Allah said: 'When you get up for prayer, perform ablution properly and make the water run between your toes and your fingers.'"
Sunan Ibn Majah Book 1, Hadith 181
← Previous Hadith "I saw the Messenger of Allah performing ablution, and he ran his little finger between his toes." (Sahih)

Another chain with similar wording.

Sunan Ibn Majah Book 1, Hadith 180 Next Hadith → "The Messenger of Allah said: perform ablution properly and let the water run between your fingers."

Sunan Ibn Majah Book 1, Hadith 182