The Saracens pressed the siege for a while very closely, but perceiving that they made no way, Abu Obeidah removed the camp about a mile's distance from the castle, hoping by this means to tempt the besieged to security and negligence in their watch, which might eventually afford him an opportunity of taking the castle by surprise. But all would not do, for Youkinna kept a very strict watch and suffered not a man to stir out. The siege continued four months, and some say five. In the mean time Omar was very much concerned, having heard nothing from the camp in Syria. He wrote, therefore, to Abu Obeidah, letting him know how tender he was over the Mussulmans, and what a great grief it was to him to hear no news of them for so long a time. Abu Obeidah answered that Kinnisrin, Hader, and Aleppo were surrendered to him, only the castle of Aleppo held out, and that they had lost a considerable number of men before it; that he had some thoughts of raising the siege, and passing forward into that part of the country which lies between Aleppo and Antioch; but only he stayed for his answer. About the time that Abu Obeidah's messengers reached Medina, there also arrived a considerable number of men out of the several tribes of the Arabs, to proffer their service to the Caliph. Omar ordered seventy camels to help their foot, and despatched them into Syria, with a letter to Abu Obeidah, in which he acquainted him "that he was variously affected, according to the different success they had met, but charged them by no means to raise the siege of the castle, for that would make them look little, and encourage their enemies to fall upon them on all sides. Wherefore," adds he, "continue besieging it till God shall determine the event, and forage with your horse round about the country."