Praise be to Allaah.
The shar'i rulings concerning relationships through breastfeeding are not the same as the rulings concerning relationships through blood ties. Breastfeeding (radaa'ah) does not mean that one is obliged to spend on those relatives, or that one is entitled to inherit from them, or that one may be a guardian for the purpose of marriage - unlike the case with ties of blood.
What they have in common is that people related in either way are forbidden to marry, and may look at one another and be alone with one another, and are regarded as mahrams for the purpose of travel.
This is the wisdom of sharee'ah, because Islam cannot give a mother who breastfed a child five times the same rights as the mother who carried him, gave birth to him, breastfed him and brought him up, and is the reason for the child's existence. Can the love, compassion and devotion in the heart of the blood mother be likened to that in the heart of the mother through breastfeeding?
There are verses of the Qur'aan which refer to that. Allaah says (interpretation of the meaning):
And We have enjoined on man (to be dutiful and good) to his parents. His mother bore him in weakness and hardship upon weakness and hardship, and his weaning is in two years
And Allaah says, after commanding the child to treat his parents well and forbidding him to do the slightest act of disobedience towards them (interpretation of the meaning):
and say: My Lord! Bestow on them Your Mercy as they did bring me up when I was young'
Hence some of the scholars said that a son through breastfeeding has to respect and honour his mother and his parents through breastfeeding, but he does not have to honour them and uphold ties with them in the same way as a son is obliged to honour his parents and relatives by blood.
There are several da'eef (weak) ahaadeeth on this topic, which we will mention here so that people may be aware of them.
1 - It was narrated that al-Tufayl (may Allaah be pleased with him) said: I saw the Prophet (peace and blessings of Allaah be upon him) sharing out some meat in al-Ji'raanah, when a woman came up to the Prophet (peace and blessings of Allaah be upon him) and he spread out her cloak for her, and she sat down on it. I said, Who is she? They said, This is his mother who breastfed him.
Narrated by Abu Dawood, 5144; classed as da'eef by al-Albaani in Da'eef Abi Dawood, 1102.
Ibn Hibbaan (10/44) included this hadeeth in a chapter which he called, Ways in which it is recommended for a person to honour the one who breastfed him when he was small.
2 - It was narrated from Umar ibn al-Saa'ib that he heard that the Messenger of Allaah (peace and blessings of Allaah be upon him) was sitting when his father through breastfeeding came to him; he spread part of his cloak for him and he sat on it. Then his mother through breastfeeding came to him and he spread part of his cloak on the other side and she sat on it. Then his brother through breastfeeding came and the Messenger of Allaah (peace and blessings of Allaah be upon him) stood up for him and made him sit in front of him.
Narrated by Abu Dawood, 5145; classed as da'eef by al-Albaani in al-Silsilah al-Da'eefah, 1120.
3 - It was narrated from Hajjaaj ibn Hajjaaj al-Aslami that his father asked the Prophet (peace and blessings of Allaah be upon him): O Messenger of Allaah, how can I repay the favour of breastfeeding? He said: (By giving) a male or female slave.
Narrated by al-Tirmidhi, 1153; al-Nasaa'i, 3329; Abu Dawood, 2064. Classed as da'eef by al-Albaani in Da'eef Abi Dawood, 445.
Al-Suyooti said in Sharh al-Nasaa'i, 6/108.
What is meant by repaying the favour of breastfeeding is the duties that are owed as a result of having been breastfed. It is as if he is asking, How can I waive the duties I owe as a result of having been breastfed so that I will have paid them off in full? They used to regard it as something good to give a gift to the wet nurse once the child had been weaned, other the wages that had be agreed upon. End quote.
4 - The biographers said that when the captive woman of Hawaazin had been gathered together, their spokesman Zuhayr ibn Sard came and said: O Messenger of Allaah, inside the enclosure are your mothers, your maternal aunts and your nursemaids. Do us a favour (and free us), may Allaah bless you.
These ahaadeeth speak of honouring and respecting, which are Islamic manners that are encouraged with regard to all Muslims. This is the reason why the Prophet (peace and blessings of Allaah be upon him) set them all free.
Al-Bidaayah wa'l-Nihaayah, 4/419
And Allaah knows best.