It is narrated from Sayyiduna Samurah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs ablution (wudu), that is sufficient and good; and whoever takes a ritual bath (ghusl), the ghusl is better."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6790