My sister has just had another daughter who is just a few days old, and my son is a year and a half old. He wants to taste her milk, so I gave him about five teaspoons. In order to be considered milk siblings, does he have to drink the milk directly from my sister's breast or could it be from a cup or spoon? And how many times? When it is said that it has to be "satisfying" (mushbi`ah), what does that mean?

Please clarify, and may Allah grant you every reward.

The prohibitionary feedings are five, due to the narration of Imam Muslim from the hadith of Aishah, who said, "Among that which was sent down of the Qur'an was that ten known feedings prohibit [that which is prohibited by blood relations]; then they were abrogated by five known [feedings]."

Therefore the prohibitionary feedings are five, and they must take place before weaning, according to the saying of the Prophet (may Allah bless him and grant him peace) to A'ishah, "See who your brothers are, for verily, breastfeeding is from hunger." In other words, it must be during the period in which the child gets hungry and fills his stomach with milk, and this is only before weaning. If it occurs after weaning, it has no effect on anything. The people of knowledge have differed over the meaning of "prohibitionary feedings" (al-rada`ât al-muharamah). Some of them said that it is to take the breast into the mouth and suck, so if the child takes the breast into his mouth, sucks and then leaves it, it would be considered one feeding. Then, if he returns, sucks and leaves the breast, it would be another feeding, and so on, even if this takes place within one sitting and in one situation, for feeding is: "the child sucking and then stopping or leaving [the breast]" because the Prophet (may Allah bless him and grant him peace) said, "One or two sucks do not prohibit [that which is prohibited by blood relations]."

Other scholars held that the "feeding" that counts is when the baby fills his stomach during each session. So, if he leaves the breast to breathe during the feeding, it would still be considered a single feeding until he eats his fill.

The preferable stance is the first in order to be on the safe side in terms of marriage.

That, and the norm of breastfeeding is that is occur directly from the breast; however, if the milk reaches the stomach by any means, it would take the same ruling, according to the hadith of breastfeeding an adult, concerning which the norm is that it not be directly from the breast due to the indisputable prohibition on that.