حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم نَحْوَهُ وَقَالَ حَبَلُ الْحَبَلَةِ أَنْ تُنْتَجَ النَّاقَةُ بَطْنَهَا ثُمَّ تَحْمِلُ الَّتِي نُتِجَتْ ‏.‏

A similar tradition has also been narrated by Ibn 'Umar from the Prophet (PBUH) through a different chain of transmitters. He said: Habal al-habalah means that a she-camel delivers an offspring and then the offspring which it delivers becomes pregnant. Translation Not Available

Book Ref: Sunan Abi Dawud Book 23 Hadith 3381
Web Ref:  Sunan Abi Dawud Book 22 Hadith 3375