Salaah is the 'key to Jannah, Wudhu is the 'key to Salaah. Without Wudhu a person cannot fulfil this great obligation. Allah Taala has clearly declared in the Qur'aan Shareef: 'O you who believe When you stand towards Salaah, wash your faces, your hands up to your elbows, make masah of your heads, and wash your feet up to the ankles.' Surah Maa'idah, aayah 6
Thus the obligation of performing Wudhu for Salaah is derived directly from the Qur'aan Shareef. The four obligatory acts of Wudhu - washing the face, washing the hands up to the elbows, making masah of the head and washing the feet...