I say, and with God's guidance: "Khalil" (interlacing) is the act of excessively ensuring that water reaches between the fingers of the hands and feet, and its ruling is that it is a Sunnah after the water has reached. However, before the water reaches, it is obligatory, as "khalil" completes the obligation of washing, since what is between the fingers is part of the hand and foot, and ensuring water reaches all parts is obligatory. Therefore, the exaggeration in ensuring this is a completion of it, making it a Sunnah; as narrated by Abu Huraira (may Allah be pleased with him) in a raised narration: "Interlace between your fingers, for Allah, the Exalted, will not interlace them for you on the Day of Resurrection in the Fire," in Sunan al-Daraqutni 1/95. And from Ibn Abbas (may Allah be pleased with him) in a raised narration: "Interlace the fingers of your hands and feet," in Musnad Ahmad 1/287, and Sheikh Shu'ayb said: Its chain is good. And from Lqit ibn Sabirah (may Allah be pleased with him) who said: "I said: O Messenger of Allah, inform me about ablution? He said: Complete the ablution, and interlace between the fingers, and exaggerate in inhaling water except when you are fasting," in Sunan al-Tirmidhi 3/155, and al-Tirmidhi said: This is a good and authentic hadith. As for the method of interlacing the fingers of the hand: it is to interlock the fingers, and for the toes: to interlace with the little finger of the left hand starting from the little toe of the right foot and ending with the little toe of the left foot. Refer to: 'Umdat al-Ri'ayah 1: 64, and Allah knows best.