This hadith has been reported on the authority of Ibn 'Umar through another chain of transmitters. (Using translation from Muslim 1501b)   

عَنْ نَافِعٍ  

[Machine] Abu Abdullah Al-Hafiz and Abu Abdur-Rahman Al-Sulami informed us, they said: Abu Al-Abbas Muhammad ibn Ya'qub narrated to us, he said: Al-Abbas ibn Muhammad Al-Dawri narrated to us, he said: Al-Hassan ibn Bishr narrated to us, he said: Al-Mu'afa ibn Imran narrated from Al-Awzai, from Ayoub ibn Musa, from Ibn Umar, who said: The Messenger of Allah ﷺ said, "Whoever presents a voluntary gift, but it becomes defective, then there is no compensation for him. But if it was a vow, then he must fulfill it." This is narrated in this chain of narration from Al-Awzai, and I think it is a fabrication, for it is only.  

أَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ وَأَبُو عَبْدِ الرَّحْمَنِ السُّلَمِيُّ قَالَا ثنا أَبُو الْعَبَّاسِ مُحَمَّدُ بْنُ يَعْقُوبَ ثنا الْعَبَّاسُ بْنُ مُحَمَّدٍ الدُّورِيُّ ثنا الْحَسَنُ بْنُ بِشْرٍ ثنا الْمُعَافَى بْنُ عِمْرَانَ عَنِ الْأَوْزَاعِيِّ عَنْ أَيُّوبَ بْنِ مُوسَى عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ قَالَ رَسُولُ اللهِ ﷺ مَنْ أَهْدَى بَدَنَةً تَطَوُّعًا فَعَطِبَتْ فَلَيْسَ عَلَيْهِ بَدَلٌ وَإنْ كَانَ نَذْرًا فَعَلَيْهِ الْبَدَلُ كَذَا رُوِيَ بِهَذَا الْإِسْنَادِ عَنِ الْأَوْزَاعِيِّ وَأَظُنُّهُ وَهْمًا فَإِنَّمَا  

[Machine] From the Messenger of Allah ﷺ who said, "Whoever performs voluntary prayers and then becomes lost (confused), he may choose (to continue) or he may leave them. And if it (the confusion) is due to a vow, then he should fulfill it (by continuing the prayers). Al-Qarqasani narrated it from Al-Awza'i, and it contradicted the consensus in its wording."  

عَنْ رَسُولِ اللهِ ﷺ قَالَ مَنْ أَهْدَى تَطَوُّعًا ثُمَّ ضَلَّتْ فَإِنْ شَاءَ أَبْدَلَهَا وَإِنْ شَاءَ تَرَكَ وَإِنْ كَانَتْ فِي نَذْرٍ فَلْيُبَدِّلْ وَرَوَاهُ الْقَرْقَسَانِيُّ عَنِ الْأَوْزَاعِيِّ فَخَالَفَ الْجَمَاعَةَ فِي مَتْنِهِ  

[Machine] On the authority of the Prophet, ﷺ , who said, "Whoever gives a voluntary gift and then withdraws it, he may eat it if he wishes, or leave it if he wishes. But if he made a vow, then he should replace it." This narration is reported by the majority, from Al-Awzaa'i, then the correct narration is from Malik, from Nafi', and Allah knows best. It has also been narrated in the first wording from Ibn Abi Zinad, from Musa bin Uqbah, from Abu Zubair, from Ibn Umar, as a Mawqoof (stopped) narration, except that its chain of narration is weak. We were informed by Abu Bakr bin Al-Harith, that I, Ali bin Umar, narrated to Qadi Al-Muhamili, who narrated to Abdullah bin Shabeeb, who narrated to Abd al-Jabbar bin Sa'id, who narrated from Ibn Abi Zinad, in which he mentioned when it goes astray...  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ أَهْدَى هَدْيًا تَطَوُّعًا ثُمَّ عَطِبَ فَإِنْ شَاءَ أَكَلَ وَإِنْ شَاءَ تَرَكَ وَإِنْ كَانَ نَذَرَ فَلْيُبَدِّلْ وَالصَّوَابُ رِوَايَةُ الْجَمَاعَةِ عَنِ الْأَوْزَاعِيِّ ثُمَّ الصَّحِيحُ رِوَايَةُ مَالِكٍ عَنْ نَافِعٍ وَاللهُ أَعْلَمُ 10260 وَقَدْ رُوِيَ بِاللَّفْظِ الْأَوَّلِ عَنِ ابْنِ أَبِي الزِّنَادِ عَنْ مُوسَى بْنِ عُقْبَةَ عَنْ أَبِي الزُّبَيْرِ عَنِ ابْنِ عُمَرَ مَرْفُوعًا إِلَّا أَنَّ إِسْنَادَهُ ضَعِيفٌ أَخْبَرَنَاهُ أَبُو بَكْرِ بْنُ الْحَارِثِ أنا عَلِيُّ بْنُ عُمَرَ ثنا الْقَاضِي الْمُحَامِلِيُّ ثنا عَبْدُ اللهِ بْنُ شَبِيبٍ ثنا عَبْدُ الْجَبَّارِ بْنُ سَعِيدٍ ثنا ابْنُ أَبِي الزِّنَادِ فَذَكَرَ فِيهِ إِذَا ضَلَّتْ  

[Machine] The Messenger of Allah ﷺ said, "Whoever guides a sacrificial animal voluntarily and it becomes defective, he should not eat from it. If he eats from it, he has to give its value in compensation. Rather, he should slaughter it, then dip its hoof in its blood, and then strike its side with it. But if it is a mandatory sacrifice, then he may eat from it if he wishes, as its sacrifice must be fulfilled." Abu Bakr ibn Khuzaimah said, "This hadith is transmitted between Abi Al-Khaleel and Abi Qatadah."  

قَالَ رَسُولُ اللهِ ﷺ مَنْ سَاقَ هَدْيًا تَطَوُّعًا فَعَطِبَ فَلَا يَأْكُلْ مِنْهُ فَإِنَّهُ إِنْ أَكَلَ مِنْهُ كَانَ عَلَيْهِ بَدَلُهُ وَلَكِنْ لِيَنْحَرْهَا ثُمَّ لِيَغْمِسْ نَعْلَهَا فِي دَمِهَا ثُمَّ لِيَضْرِبْ بِهَا جَنْبَهَا وَإِنْ كَانَ هَدْيًا وَاجِبًا فَلْيَأْكُلْ إِنْ شَاءَ فَإِنَّهُ لَا بُدَّ مِنْ قَضَائِهِ قَالَ أَبُو بَكْرِ بْنُ خُزَيْمَةَ هَذَا الْحَدِيثُ مُرْسَلٌ بَيْنَ أَبِي الْخَلِيلِ وَبَيْنَ أَبِي قَتَادَةَ رَجُلٌ  

[Machine] She lost two of her camels, so Abdullah bin Zubayr sent two others and slaughtered them. Then she found the two camels that were lost and slaughtered them.  

أَنَّهَا ضَلَّتْ لَهَا بَدَنَتَانِ فَأَرْسَلَ عَبْدُ اللهِ بْنُ الزُّبَيْرِ بِأُخْرَيَيْنِ فَنَحَرَتْهُمَا ثُمَّ وَجَدَتْ بَعْدَ ذَلِكَ اللَّتَيْنِ ضَلَّتَا فَنَحَرَتْهُمَا