There are those who say that the rule concerning a friend's wife on this issue is the same as for the friend, and one must stand up before her, and some who say that it is not imperative but that it should be done - out of piety. It is appropriate to rise in the first sense; it says in Sha'ar Hamiztvot that "you shall fear your God". Fear in the heart was said concerning women, and rising or praising is unnecessary. These words apply to aged women and to wise women, but it is obligatory to stand before the wife of a talmid hacham [Torah scholar] out of respect for her husband, since she is likened to his body and her case is considered as is standing before her husband. Know that even somebody who considers a friend's wife like his friend on this matter will admit that nobody they did not say that an elder's wife is like the elder, because the honor of the Torah is different, and this is as simple as it is clear.