Narrated Abdullah ibn Masud: The extent of the shadow when the Messenger of Allah prayed (the noon prayer) was three to five feet in summer and five to seven feet in winter.
Hadith Referenceسنن ابي داود / كتاب الصلاة / 400
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:إسناده حسن, مشكوة المصابيح (586)