Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that during a journey which we undertook in the company of the Prophet Muhammad (peace be upon him), the Prophet (peace be upon him) lagged behind us. Then he (peace be upon him) met us while we had delayed the prayer and were performing ablution, so (due to haste) we began to pass water over our feet (because washing them takes time). Upon this, the Prophet (peace be upon him) raised his voice and said two or three times: "Woe to the heels from the fire (of punishment)" (i.e., if left dry).