The times when prayer is forbidden do not include wudoo’
Question

Your preparation for prayer is like your prayer according to many hadeeths. Does this mean that it is forbidden to make ablution at sunrise/sunset/12am/12pm or is it permissible? And if one is reading a lengthy obligatory prayer· and the time for sunset/sunrise· etc. occurs· should one break the prayer and start again· or carry on? Also· if one is for example reading lengthy tarawih prayers· and they don't finish until after 12pm· do they need to make another ablution after 12pm or does it not matter as they are essentially reading the same salaat?
Praise be to Allah.Firstly: 
It was reported in Saheeh al-Imam Muslim that ‘Uqbah ibn ‘Aamir said: “There are three times when the Messenger of Allah (peace and blessings of Allah be upon him) used to forbid us to pray or to bury our dead: when the sun begins to rise until it is fully up; when the sun is at its height at midday until it passes over the meridian; and when the sun draws near to setting until it sets.” (Salaat al-Musaafireen wa Qasruhaa, 1373). 
What is forbidden in this hadeeth is prayer and burying the dead. Wudoo’ does not come under the same rulings as prayer at all, because prayer means worshipping Allah with certain words and actions, starting with the takbeer and ending with the tasleem. 
This is what is meant by what is forbidden in this hadeeth, not wudoo’. Comparing wudoo’ with prayer in this prohibition is comparing two things which are not alike, and this is incorrect. If a person speaks whilst making wudoo’, this does not make his wudoo’ invalid, whereas speaking invalidates one’s prayer. And there are other differences between prayer and wudoo’. The point is that it is incorrect to compare wudoo’ to prayer and say that it is forbidden at these times; rather it is recommended (mustahabb) for a person to have wudoo’ (be taahir or pure) at all times. 
Secondly: 
One should not stop praying an obligatory prayer if you are praying and the time of sunrise or sunset is close. That is because you have caught up with the prayer at the right time if you catch up with one rak’ah of it in its right time. If a person is praying Fajr, for example, and he makes the first rak’ah long, then he starts the second rak’ah and makes it long, and the sun rises (during the second rak’ah), in this case his action is OK, and he has performed the prayer at the right time. But if the sun rises when he has not completed the first rak’ah, then he has not prayed at the right time and he has sinned by making the rak’ah too long. The same may said with regard to ‘Asr and all the other prayers. 
Thirdly: 
If a person has wudoo’ and it has not been “broken” by any of the things that nullify wudoo’, then he does not have to repeat his wudoo’. It was proven that the Prophet (peace and blessings of Allah be upon him) prayed all five prayers on the day of Conquest of Makkah with one wudoo’. 
It was narrated from Sulaymaan ibn Buraydah from his father that the Prophet (peace and blessings of Allah be upon him) prayed all the prayers on the day of the Conquest of Makkah with one wudoo’, and he wiped over his leather slippers (when making wudoo’). ‘Umar said to him, “You have done something today that you never did before.” He said, “I did it deliberately, O ‘Umar.”
(Narrated by Muslim, 277) 
Al-Nawawi said: 
This hadeeth includes various kinds of knowledge, such as: it is permissible to wipe over the socks; it is permissible to pray the obligatory and naafil (supererogatory) prayers with one wudoo’, so long as it is not broken, and this is permissible according to the consensus of those (scholars) whose opinions carry weight. 
Abu Ja’far al-Tahhaawi and Abu’l-Hasan ibn Battaal narrated in Sharh Saheeh al-Bukhaari that a group of the scholars said that it is obligatory to do wudoo’ for each prayer, even if one already has wudoo’, basing that on the aayah (interpretation of the meaning): 
“When you intend to offer As-Salaah (the prayer), wash your faces and your hands (forearms) up to the elbows, rub (by passing wet hands over) your heads, and (wash) your feet up to the ankles”
[al-Maa’idah 5:6]! 
I do not think that this view has been narrated with a saheeh isnaad from anyone. Perhaps they meant that it is mustahabb to renew one’s wudoo for every prayer. 
The evidence of the majority is the saheeh ahaadeeth, including this hadeeth (the hadeeth of ‘Umar). 
And the hadeeth of Anas in Saheeh al-Bukhaari: “The Messenger of Allah (peace and blessings of Allah be upon him) used to do wudoo’ for every prayer, but one of us would regard his (previous) wudoo’ as sufficient so long as he had not broken it.” 
And the hadeeth of Suwayd ibn al-Nu’maan, also in Saheeh al-Bukhaari: “The Messenger of Allah (peace and blessings of Allah be upon him) prayed ‘Asr, then he ate saweeq, then he prayed Maghrib without doing wudoo’.” 
There are many similar ahaadeeth, such as the hadeeth about combining prayers in ‘Arafah and al-Muzdalifah, and on all journeys, and joining the prayers which were missed on the day of al-Khandaq, and so on. 
What is meant by the aayah quoted above – and Allah knows best – is that if you intend to pray and you have broken your wudoo’, then you should do wudoo’. And it was said that this was abrogated by the actions of the Prophet (peace and blessings of Allah be upon him), but this view is da’eef (weak). And Allah knows best. 
With regard to the words of ‘Umar (may Allah be pleased with him), “You have done something today that you never did before” – this clearly indicates that the Prophet (peace and blessings of Allah be upon him) regularly used to do wudoo’ for each prayer, doing that which is best. But on this day he prayed all the prayers with one wudoo’, to show that it is permissible to do so, as he (peace and blessings of Allah be upon him) said, “I did it deliberately, O ‘Umar.” 
Sharh Muslim, 3/177, 178) 
And Allah knows best