Al-Matalib al-'Aliyah 92 — Running the fingers through the fingers

It is narrated from Mus'ab (may Allah have mercy on him) that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) saw some people performing ablution and said to them (teaching them the etiquettes of ablution): "Do khilal." He meant doing khilal to make water reach between the fingers.
The chain of this report (athar) is sahih. Imam Ibn Abi Shaybah narrated it in al-Musannaf (hadith: 106), and all its narrators are thiqat (trustworthy).