Wudu (Ablution)
Quick Answer
Purification, protection from harm, and completion of goals.
Classical Interpretation (Ibn Sirin)
Performing Wudu (ablution) perfectly in a dream signifies the washing away of sins, protection from enemies, and the fulfillment of one's needs. It is a sign of spiritual and physical purity. Doing Wudu with something other than clean water (like milk or dirty water) indicates an innovation in religion or an invalid action. Completing Wudu means completing a goal.
Quranic Context
"...Allah does not intend to make difficulty for you, but He intends to purify you and complete His favor upon you... (Quran 5:6)"