Du Chongwei
At that time, Shi was also faced with the prospect that An Chongrong the military governor of Chengde Circuit (成德, headquartered in modern Shijiazhuang, Hebei), who was antagonistic toward the Khitan (whose state had been renamed Liao by that point), was repeatedly trying to provoke Emperor Taizong, including aligning with the Tuyuhun tribesmen within Liao territory (that was ceded to Liao as part of Shi's agreement to cede the northern territories to Liao). An, in his rhetoric, was also rebuking Shi for being overly groveling to Liao and urging him to turn against Liao. Shi was initially hesitant to take action, because of An's military strength. Sang, hearing this, submitted a secret petition to Shi pointing out that it had been Khitan military strength that allowed him to establish his state, and he therefore should not turn against Liao — and further pointed out that An could be defeated if he rebelled. He encouraged Shi to temporarily move his court to Yedu, so that he could react against An quickly. Shi agreed and thanked Sang for his advice. When An subsequently rebelled, Shi, at Yedu, was able to send his brother-in-law Du Chongwei to crush An's rebellion quickly. After An's defeat, Sang went to Yedu to pay homage to Shi, and was thereafter made the military governor of Jinchang Circuit (晉昌, headquartered in modern Xi'an, Shaanxi).