Yahya said, "I heard Malik say that if a man pledges his garden
for a stated period and the fruits of that garden are ready before the
end of that period, the fruits are not included in the pledge with the
real estate, unless it is stipulated by the pledger in his pledge.
However, if a man receives a slave-girl as a pledge and she is
pregnant or she becomes pregnant after his taking her as a pledge, her
child is included with her.
"A distinction is made between the fruit and the child of the slave-girl. The Messenger of Allah, may Allah bless him and grant him peace, said, 'If someone sells a palm which has been pollinated, the fruit belongs to the seller unless the buyer stipulates its inclusion.' The undisputed way of doing things in our community is that if a man sells a slave-girl or an animal with a foetus in its womb, the foetus belongs to the buyer, whether or not the buyer stipulates it. The palm is not like the animal. Fruit is not like the foetus in its mother's womb. Part of what clarifies that is also that it is the usage of people to have a man pawn the fruit of the palm apart from the palm. No one pawns the foetus in its mother's womb whether of slaves or animals."
"A distinction is made between the fruit and the child of the slave-girl. The Messenger of Allah, may Allah bless him and grant him peace, said, 'If someone sells a palm which has been pollinated, the fruit belongs to the seller unless the buyer stipulates its inclusion.' The undisputed way of doing things in our community is that if a man sells a slave-girl or an animal with a foetus in its womb, the foetus belongs to the buyer, whether or not the buyer stipulates it. The palm is not like the animal. Fruit is not like the foetus in its mother's womb. Part of what clarifies that is also that it is the usage of people to have a man pawn the fruit of the palm apart from the palm. No one pawns the foetus in its mother's womb whether of slaves or animals."
Muwatta Malik Book 36, Hadith 18