Note 527 — Chapter XXXIX · BATTLE OF SIFFIN. A.H. XXXVI., XXXVII. A.D. 657.
Reading edition
The western detachment, 12,000 strong, was forced by the hostile attitude of Syria hastily to retrace its steps as far as Hît, where they recrossed the river, and then marched north through Mesopotamia. They were so long delayed that Aly, with the main body, reached Ricca first, and, on seeing them come up, naïvely exclaimed, ‘Lo, here is my advanced column in the rear!’
The main body took the Tigris route, perhaps as affording better forage at that dry season of the year.