Wai 外: those outside the clan, not related by blood, ‘outsiders’, those with different surname. In oracle bone inscriptions wai was used as a prefix for former kings that were not from the direct lineal line (Liu Xinglong 刘兴隆, 新编甲骨文字典, p. 404) The expression waisun 外孫 referred to the children of one’s daughter: when a daughter married she took the surname of her husband and from that moment she (and her children) belonged to the other clan (金文常用字典, p. 700; 王力古漢語字典, p. 176).
In manuscripts from the Warring States period wai is also used as a loan for gui 禬: a sacrifice, ritual or prayer to dispel disasters and sickness (Bai Yulan 白於藍 (ed.), 戰國秦漢簡帛古書通假字彙纂, p. 527; 王力古漢語字典, p. 836-837; 漢語大詞典, Vol. 7, p. 966).
Some may wonder why I translate wai as ‘outsiders’ but choose to translate nei 內 in line 2 as ‘women (of the emperor)’ when ‘insiders’ would also be a plausible translation. My choice is decided by the structure of the sentences. Line 2 says
while line 4 says
In line 2 the joining/bonding comes from (zi 自) inside, the text does not talk about joining/bonding with inside. Line 4 however says that wai, ‘outside’ is joining.
Bi 比: see line 1.
Outsiders joining. Auspicious divination.