Conduct with family members - For the sake of Heaven

The Gemara relates: Rav Aḥa bar Abba arrived at the house of Rav Ḥisda, his son-in-law. He took his grand-daughter and placed her on his lap. Rav Ḥisda said to him: Doesn’t the Master think that she might already be betrothed? Rav Aḥa said to him: If that is true, you have transgressed the ruling of Rav, as Rav Yehuda says that Rav says, and some say it was said by R. Elazar: It is prohibited for a man to betroth his daughter when she is a minor, until she grows up and says: I want to marry so-and-so, as otherwise she might reject the designated husband and ultimately sin by committing adultery. Rav Ḥisda replied: The Master has likewise transgressed the words of Shmuel. As Shmuel says: One may not make use of a woman, so how can you hold her on your lap? He said to him: I hold in accordance with another statement of Shmuel, as Shmuel says: All such actions are permitted for the sake of Heaven. If one is acting out of familial affection, without any element of licentiousness, it is permitted.

All for the sake of Heaven - And on this we rely nowadays that we are served by women.

It is forbidden to be served by a woman at all, whether she is an adult or a minor, whether a slave or free, lest he come to have forbidden thoughts. What service were they speaking of? Washing his face, hands, and feet, even to pour water so he can wash his face, hands, and feet, even if she does not touch him; or making his bed in front of him; or pouring a drink. Rem"a: Some say that eating with her with a bowl is also forbidden with every erva, as with his menstrually impure wife.

There are those who are lenient in all of this; that they only prohibited affectionate things with one's menstrually impure wife.

Some say that all this is forbidden only when they are alone, but in a place like a bathhouse where many people are found, one may be washed by an idolatrous slave woman, and this is the custom. And some say that anything not done in a affectionate manner (בדרך חבה), where his intent is only for Heaven's sake, is permitted. Thus the custom is to be lenient in these things. Some say that one should not do affectionate things even with his wife, such as to inspect her head for lice, in front of others.)

The Gemara relates that Ulla, when he would come from the house of his teacher, would kiss his sisters on their bosom. And some say: On their hands. Ulla was not concerned about violating the prohibition of displaying affection toward a relative, as his intention was not to have relations with them. The Gemara adds that his action was in contradiction to a saying of his, as Ulla said: Even any intimacy is prohibited with a woman with whom he is forbidden to engage in sexual relations due to the reason formulated as an adage: Go around, go around, and do not approach the vineyard, they say to the nazirite. They advise the nazirite, who is forbidden to consume any product of a vine, that he should not even approach the vineyard. The same is true with regard to the prohibition of forbidden relations. According to Ulla, one must distance himself from them to whatever degree possible.

[Editor Note: it is curious that some rule according to Ulla's directive, but not according to his public conduct. Since the Rama already ruled in accordance with Tosofot above, it may apply to this rule as well; we rule according to Tosofot & Ulla's public conduct [See Rambam; See Ramban.]