Al-Mundhiri recorded the following chapter in his book Al-Targhib wal-Tarhib:

الترغيب في المحافظة على الوضوء وتجديده

Encouragement to maintain ablution and to renew it.

Source: al-Targhīb wal-Tarhīb 1/162

Abdullah ibn Amr reported: The Messenger of Allah, peace and blessings be upon him, said:

اسْتَقِيمُوا وَلَنْ تُحْصُوا وَاعْلَمُوا أَنَّ مِنْ أَفْضَلِ أَعْمَالِكُمْ الصَّلَاةَ وَلَا يُحَافِظُ عَلَى الْوُضُوءِ إِلَّا مُؤْمِنٌ

Remain upright, though you cannot encompass it entirely. Know that most favorable of your deeds is prayer and that none can preserve his ablution but a believer.

Source: Sunan Ibn Mājah 278, Grade: Sahih

Thawban reported: The Messenger of Allah, peace and blessings be upon him, said:

اسْتَقِيمُوا وَلَنْ تُحْصُوا وَاعْلَمُوا أَنَّ خَيْرَ أَعْمَالِكُمْ الصَّلَاةَ وَلَا يُحَافِظُ عَلَى الْوُضُوءِ إِلَّا مُؤْمِنٌ

Remain upright, though you cannot encompass it entirely. Know that the best of your good deeds is prayer and that none can preserve his ablution but a believer.

Source: Sunan Ibn Mājah 277, Grade: Sahih

Al-Nawawi said:

اتَّفَقَ أَصْحَابُنَا عَلَى اسْتِحْبَابِ تَجْدِيدِ الْوُضُوءِ وَهُوَ أَنْ يَكُونَ عَلَى وُضُوءٍ ثُمَّ يَتَوَضَّأُ مِنْ غَيْرِ أَنْ يُحْدِثَ

Our scholars agreed upon the recommendation to renew ablution, which is that one with ablution later performs it again, without having lost his ritual purification.

Source: al-Majmū’ Sharḥ al-Muhadhab 1/469

Abu Umamah reported: The Messenger of Allah, peace and blessings be upon him, said:

اسْتَقِيمُوا وَنِعِمَّا إِنْ تَسْتَقيِمُوا وَخَيْرُ أَعْمَالِكُمُ الصَّلَاةُ وَلَا يُحَافِظُ عَلَى الْوُضُوءِ إِلَّا مُؤْمِنٌ

Remain upright and it is a blessing if you can do so. The best of your good deeds is prayer and none can preserve his ablution but a believer.

Source: Sunan Ibn Mājah 279, Grade: Sahihli ghayrihi

Al-Munawi commented on this tradition, writing:

يُحَافِظُ عَلَى الْوُضُوءِ الظَّاهِرِيِّ وَالْبَاطِنِيِّ فَالظَّاهِرِيُّ ظَاهِرٌ وَالْبَاطِنِيُّ طَهَارَةُ السِّرِّ عَنِ الْأَغْيَارِ

Preserving ablution means outwardly and inwardly. Outwardly are its external components and inwardly is purification of the inner-self from impurities.

Source: Fayḍ al-Qadīr 994

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said:

لَوْلَا أَنْ أَشُقَّ عَلَى أُمَّتِي لَأَمَرْتُهُمْ عِنْدَ كُلِّ صَلَاةٍ بِوُضُوءٍ أَوْ مَعَ كُلِّ وُضُوءٍ سِوَاكٌ وَلَأَخَّرْتُ عِشَاءَ الْآخِرَةِ إِلَى ثُلُثِ اللَّيْلِ

Were it not hardship upon my nation, I would have commanded them to perform ablution with every prayer or to use the toothstick with every ablution.

Source: Musnad Aḥmad 7461, Grade: Sahih

Abu Huraira reported: The Prophet, peace and blessings be upon him, said:

يَا بِلَالُ حَدِّثْنِي بِأَرْجَى عَمَلٍ عَمِلْتَهُ فِي الْإِسْلَامِ فَإِنِّي سَمِعْتُ دَفَّ نَعْلَيْكَ بَيْنَ يَدَيَّ فِي الْجَنَّةِ

O Bilal, tell me of the most hopeful deed you practiced in Islam. I heard the scuffle of your sandals before me in Paradise.

Bilal, may Allah be pleased with him, said:

مَا عَمِلْتُ عَمَلًا أَرْجَى عِنْدِي أَنِّي لَمْ أَتَطَهَّرْ طَهُورًا فِي سَاعَةِ لَيْلٍ أَوْ نَهَارٍ إِلَّا صَلَّيْتُ بِذَلِكَ الطُّهُورِ مَا كُتِبَ لِي أَنْ أُصَلِّيَ

The most hopeful deed to me is that I do not perform ablution by day or night that I pray along with it as much as Allah decreed me to pray.

Source: Ṣaḥīḥ al-Bukhārī 1098, Grade: Muttafaqun Alayhi

Al-Nawawi commented on this tradition, writing:

وَفِيهِ فَضِيلَةُ الصَّلَاةِ عَقِبَ الْوُضُوءِ وَأَنَّهَا سُنَّةٌ وَأَنَّهَا تُبَاحُ فِي أَوْقَاتِ النَّهْيِ عِنْدَ طُلُوعِ الشَّمْسِ وَاسْتِوَائِهَا وَغُرُوبِهَا وَبَعْدَ صَلَاةِ الصُّبْحِ وَالْعَصْرِ لِأَنَّهَا ذَاتُ سَبَبٍ

In this is the virtue of praying after finishing ablution, that it is Sunnah, and that it is permissible to do so at the times when prayer is generally prohibited, such as at the rising of the sun, its zenith, and its setting, after the morning and midday prayers, because it has a reason to allow it.

Source: Sharḥ al-Nawawī ‘alá Ṣaḥīḥ Muslim 2458

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said:

لَا صَلَاةَ لِمَنْ لَا وُضُوءَ لَهُ وَلَا وُضُوءَ لِمَنْ لَمْ يَذْكُرْ اسْمَ اللَّهِ تَعَالَى عَلَيْهِ

There is no prayer for one without ablution, and there is no ablution for one without mentioning the name of Allah before it.

Source: Sunan Abī Dāwūd 101, Grade: Sahih

Al-Marghinani commented on this tradition, saying:

لا وضوء لمن لم يسم الله والمراد به نفي الفضيلة والأصح أنها مستحبة

No ablution without mentioning the name of Allah means a negation of perfection; the more correct opinion is that it is recommended.

Source: al-Hidāyah 1/15