Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
malik:23-13Mālik > Nāfiʿ

Yahya related to me from Malik from Nafi that Abdullah ibn Umar did not sacrifice for the child in the womb. Malik said, "The sacrifice is sunna, and it is not obligatory. I prefer that anyone who has the price of the animal should not abandon it.''  

مالك:٢٣-١٣وَحَدَّثَنِي عَنْ مَالِكٍ عَنْ نَافِعٍ

أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ لَمْ يَكُنْ يُضَحِّي عَمَّا فِي بَطْنِ الْمَرْأَةِ قَالَ مَالِكٌ الضَّحِيَّةُ سُنَّةٌ وَلَيْسَتْ بِوَاجِبَةٍ وَلاَ أُحِبُّ لأَحَدٍ مِمَّنْ قَوِيَ عَلَى ثَمَنِهَا أَنْ يَتْرُكَهَا