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.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
suyuti:1577a –

Messenger of Allah said: "When performing Wudu go between the fingers of your hands and (toes of) your feet." (Using translation from Tirmidhī 39)   

السيوطي:١٥٧٧a –

"إذَا توضَّأتَ فخلِّل أصابعَ يديكَ ورجْلَيكَ".  

[حم] أحمد [ت] الترمذي حسن غريب، [ك] الحاكم في المستدرك عن ابن عباس

See similar narrations below:

Collected by Tirmidhī, Aḥmad, Ḥākim, Suyūṭī
tirmidhi:39 – Ibrāhīm b. Saʿīd > al-Jawharī > Saʿd b. ʿAbd al-Ḥamīd b. Jaʿfar > ʿAbd al-Raḥman b. Abū al-Zinād > Mūsá b. ʿUqbah > Ṣāliḥ a freed slave of al-Tawʾamah > Ibn ʿAbbās > Rasūl

Messenger of Allah said: "When performing Wudu go between the fingers of your hands and (toes of) your feet."  

Abū ʿĪsá said that this Ḥadīth is Ḥasan-Gharīb.
الترمذي:٣٩ – حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعِيدٍ هُوَ الْجَوْهَرِيُّ حَدَّثَنَا سَعْدُ بْنُ عَبْدِ الْحَمِيدِ بْنِ جَعْفَرٍ حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ أَبِي الزِّنَادِ عَنْ مُوسَى بْنِ عُقْبَةَ عَنْ صَالِحٍ مَوْلَى التَّوْأَمَةِ عَنِ ابْنِ عَبَّاسٍ

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا تَوَضَّأْتَ فَخَلِّلْ بَيْنَ أَصَابِعِ يَدَيْكَ وَرِجْلَيْكَ  

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ
ahmad:16381 – Wakīʿ > Sufyān > Abū Hāshim Ismāʿīl b. Kathīr > ʿĀṣim b. Laqīṭ b. Ṣabirah from his father

[Machine] I came to the Prophet ﷺ , and he said, "When you perform ablution, separate your fingers."  

أحمد:١٦٣٨١ – حَدَّثَنَا وَكِيعٌ قَالَ حَدَّثَنَا سُفْيَانُ عَنْ أَبِي هَاشِمٍ إِسْمَاعِيلَ بْنِ كَثِيرٍ عَنْ عَاصِمِ بْنِ لَقِيطِ بْنِ صَبِرَةَ عَنْ أَبِيهِ قَالَ

أَتَيْتُ النَّبِيَّ ﷺ فَقَالَ إِذَا تَوَضَّأْتَ فَخَلِّلِ الْأَصَابِعَ  

hakim:647 – Abū al-ʿAbbās Muḥammad b. Yaʿqūb > Asad b. ʿĀṣim > al-Ḥusayn b. Ḥafṣ > Sufyān

The Messenger of Allah ﷺ said: "When you perform Wudu', do so properly, and wash in between the fingers (Al-Asabi')."[2] [1] Al-Asabi' is plural meaning fingers as well as toes, and the author mentioned only one narration on the topic whereas some of them clarify "of the hands and feet." So he mentioned the general wording amids chapters how to wash the feet. [2] Part of this narration preceded under No. 87. (Using translation from Nasāʾī 114)   

الحاكم:٦٤٧ – حَدَّثَنَا أَبُو الْعَبَّاسِ مُحَمَّدُ بْنُ يَعْقُوبَ ثنا أَسَدُ بْنُ عَاصِمٍ ثنا الْحُسَيْنُ بْنُ حَفْصٍ عَنْ سُفْيَانَ وَأَخْبَرَنَا أَبُو بَكْرِ بْنُ مُحَمَّدٍ الصَّيْرَفِيُّ ثنا عَبْدُ الصَّمَدِ بْنُ الْفَضْلِ ثنا قَبِيصَةُ ثنا سُفْيَانُ وَأَخْبَرَنَا أَحْمَدُ بْنُ جَعْفَرٍ الْقَطِيعِيُّ ثنا عَبْدُ اللَّهِ بْنُ أَحْمَدَ بْنِ حَنْبَلٍ حَدَّثَنِي أَبِي ثنا وَكِيعٌ ثنا سُفْيَانُ عَنْ أَبِي هَاشِمٍ عَنْ عَاصِمِ بْنِ لَقِيطِ بْنِ صَبِرَةَ عَنْ أَبِيهِ قَالَ

قَالَ رَسُولُ اللَّهِ ﷺ «إِذَا تَوَضَّأْتَ فَخَلِّلِ الْأَصَابِعَ»  

«هَذَا حَدِيثٌ قَدِ احْتَجَّا بِأَكْثَرِ رُوَاتِهِ ثُمَّ لَمْ يُخَرِّجَاهُ لِتَفَرُّدِ عَاصِمِ بْنِ لَقِيطِ بْنِ عَامِرِ بْنِ صَبِرَةَ عَنْ أَبِيهِ بِالرِّوَايَةِ وَقَدْ قَدَّمْنَا الْقَوْلَ فِيهِ وَلَهُ شَاهِدٌ» لم يخرجاه لتفرد عاصم بأبيه وله شاهد