It is narrated from Sayyiduna Mujahid (may Allah have mercy on him) that the son of Sayyiduna Ibn Umar (may Allah be pleased with them both) — Abu Bakr or Umar — sneezed and said: "Aab." Sayyiduna Ibn Umar (may Allah be pleased with them both) said: "What is 'Aab'? 'Aab' is the name of one of the devils, which he has placed between sneezing and «الحمد للہ»."
Hadith Referenceالادب المفرد / كتاب العطاس والتثاؤب / 937