《礼记·丧大记》
国君死，尚未小敛，如果此时有寄公、国宾前来吊唁，孝子要出迎。大夫死，尚未小敛，如桌此时国君派人前来吊唁或送礼，孝子要出迎。
君之丧，未小敛，为寄公国宾出；大夫之丧，未小敛，为君命出；士之丧，于大夫不当敛而出。
At the death of a state monarch, if he has not undergone a small encoffinment when a guest of the state or a diplomatic envoy comes to pay respects, the filial son must go to receive them. At the death of a duke, if he has not undergone a small encoffinment when the state monarch sends someone to pay respects or give a gift, the filial son must go to receive him.