Hadith #4 (Jami' al-Tirmidhi)
Book: The Book on Purification
Narrator(s): Jabir ibn 'Abdullah, Mujahid bin Jabir مجاهد بن جبر, Sulaiman bin Qrm سليمان بن قرم

Allah’s Messenger said: “The key to Paradise is Salat, and the key to Salat is Wudu’.”

Source: https://parallelquran.com/hadith/jami-al-tirmidhi-4/