Sufyan bin Uyaynah narrates from Asim that Sayyiduna Wa'il (may Allah be pleased with him) said: Then I came to them in the winter season, and I saw that they raised their hands (when doing raf' al-yadayn) inside their cloaks.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2322