✅Answer: Pay attention to the verse related to breastfeeding and some narrations:

In the name of Allah, the Most Gracious, the Most Merciful

وَالْوَالِدَاتُ یُرْضِعْنَ أَوْلَادَهُنَّ حَوْلَیْنِ کَامِلَیْنِ لِمَنْ أَرَادَ أَن یُتِمَّ الرَّضَاعَةَ ۚ وَعَلَی الْمَوْلُودِ لَهُ رِزْقُهُنَّ وَکِسْوَتُهُنَّ بِالْمَعْرُوفِ ۚ لَا تُکَلَّفُ نَفْسٌ إِلَّا وُسْعَهَا ۚ لَا تُضَارَّ وَالِدَةٌ بِوَلَدِهَا وَلَا مَوْلُودٌ لَّهُ بِوَلَدِهِ ۚ وَعَلَی الْوَارِثِ مِثْلُ ذَٰلِکَ، فَإِنْ أَرَادَا فِصَالًا عَن تَرَاضٍ مِّنْهُمَا وَ تَشَاوُرٍ فَلَا جُنَاحَ عَلَیْهِمَا......... (۲۳۳) ۞

📖 Surah Al-Baqarah

Mothers shall breastfeed their children for two full years. This is for those who wish to complete the period of nursing. The father is responsible for their food and clothing in a proper and suitable manner. No one is burdened beyond their capacity. No mother should suffer harm because of her child, and no father should suffer harm because of his child. And the same rulings apply to the heirs. So if they wish, by mutual consent and consultation, to wean the child earlier, there is no sin upon them… (2:233)

1 عَنْ عَبْدِ الْوَهَّابِ بْنِ الصَّبَّاحِ قَالَ: قَالَ أَبُو عَبْدِ اللَّهِ الْفَرْضُ فِي الرَّضَاعِ أَحَدٌ وَ عِشْرُونَ شَهْراً فَمَا نَقَصَ عَنْ أَحَدٍ وَ عِشْرِينَ شَهْراً فَقَدْ نَقَصَ الْمُرْضِعُ وَ إِنْ أَرَادَ أَنْ يُتِمَّ الرَّضَاعَةَ فَحَوْلَيْنِ كَامِلَيْنِ.

📚 Al-Tahdhib, vol.8, p.106

Imam al-Sadiq (peace be upon him) said: The prescribed duration for breastfeeding is 21 months. Anything less than 21 months is considered incomplete. If one wishes to complete it, they should breastfeed for the full two years.

2 عَنِ الْحَلَبِيِّ عَنْ أَبِي عَبْدِ اللَّه فِي حَدِيثٍ أَنَّهُ نَهَى أَنْ يُضَارَّ بِالصَّبِيِّ أَوْ تُضَارَّ أُمُّهُ فِي رَضَاعِهِ وَ لَيْسَ لَهَا أَنْ تَأْخُذَ فِي رَضَاعِهِ فَوْقَ حَوْلَيْنِ كَامِلَيْنِ فَإِنْ أَرَادَا فِصَالًا عَنْ تَرَاضٍ مِنْهُمَا قَبْلَ ذَلِكَ كَانَ حَسَناً وَ الْفِصَالُ هُوَ الْفِطَامُ.

📚 Al-Kafi, vol.6, p.103

Halabi narrated in a hadith that Imam al-Sadiq (peace be upon him) forbade causing harm to the child or to the mother during breastfeeding. It is not permissible for the woman to receive more than the full two years for breastfeeding. If the husband and wife mutually agree to wean the child before that period, it is acceptable. 'Fisal' refers to the act of weaning.

3 عَنْ سَعْدِ بْنِ سَعْدٍ الْأَشْعَرِيِّ عَنْ أَبِي الْحَسَنِ الرِّضَا قَالَ: سَأَلْتُهُ عَنِ الصَّبِيِّ هَلْ يُرْضَعُ أَكْثَرَ مِنْ سَنَتَيْنِ فَقَالَ عَامَيْنِ فَقُلْتُ فَإِنْ زَادَ عَلَى سَنَتَيْنِ هَلْ عَلَى أَبَوَيْهِ مِنْ ذَلِكَ شَيْ ءٌ قَالَ لَا.

📚 Al-Kafi, vol.6, p.41

Sa‘d ibn Sa‘d said: I asked Imam al-Ridha (peace be upon him) about a child — can breastfeeding extend beyond two lunar years? He replied: No, the limit is two years. I asked if breastfeeding beyond two lunar years would impose anything upon the father or mother? He replied: No.

4 عَنْ سَمَاعَةَ عَنْ أَبِي عَبْدِ اللَّه قَالَ: الرَّضَاعُ وَاحِدٌ وَ عِشْرُونَ شَهْراً فَمَا نَقَصَ فَهُوَ جَوْرٌ عَلَى الصَّبِيِّ

📚 Al-Kafi, vol.6, p.40

Imam al-Sadiq (peace be upon him) said: Breastfeeding is 21 months, and anything less than this is considered injustice and oppression toward the child.

✅From the above verse and narrations, it is clear that the full duration of breastfeeding is two lunar years. It is also permissible to shorten it by three months, making the period 21 months. Less than this constitutes injustice toward the child. According to the narrations, it is also permissible for parents to hire a wet nurse for their child, which has its own specific rulings.

اَللّهُمَّ عَجِّل لِوَلیِّکَ الفَرَجَ وَ العافیَةَ وَ النَّصرَ