Praise be to Allaah.

Firstly: 

Prayer is very important, and it is enjoined to pray regularly on time; we are encouraged to do that and warned against taking this matter lightly, as is well known. For example, Allaah says (interpretation of the meaning): 

“Verily, As‑Salaah (the prayer) is enjoined on the believers at fixed hours”

[al-Nisa’ 4:103]. 

And the Prophet (peace and blessings of Allaah be upon him) said, when asked which deed is most beloved to Allaah: “Prayer offered on time.”  Narrated by al-Bukhaari (527) and Muslim (85). 

With regard to praying ‘Asr, in particular, on time, Allaah says (interpretation of the meaning): 

“Guard strictly (five obligatory) As‑Salawaat (the prayers) especially the middle Salaah (i.e. the best prayer ‑ ‘Asr). And stand before Allaah with obedience [and do not speak to others during the Salaah (prayers)]”

[al-Baqarah 2:238].  

The middle prayer is ‘Asr, as was stated in a saheeh report from the Prophet (peace and blessings of Allaah be upon him). 

He (peace and blessings of Allaah be upon him) said: “The one who omits to pray ‘Asr, all his good deeds will be lost.” Narrated by al-Bukhaari (553). 

Once this is established, the questioner  should do all that he can to look for means that will enable him to perform this great duty at the right time, such as choosing the time of lectures that do not conflict with prayer, and asking permission from the lecturer to leave the room to perform the prayer in any clean place. It is well known that praying does not take up more than a few minutes. 

You should beware of failing to go out and pray out of shyness or weakness, or because you do not want to show that you are a Muslim. The scholars have stated that if the one who is living in a kaafir country cannot practise his religion openly, then he is obliged to migrate and it is not permissible for him to stay, unless he is unable to migrate, because Allaah says (interpretation of the meaning): 

“Verily, as for those whom the angels take (in death) while they are wronging themselves (as they stayed among the disbelievers even though emigration was obligatory for them), they (angels) say (to them): ‘In what (condition) were you?’ They reply: ‘We were weak and oppressed on the earth.’ They (angels) say: ‘Was not the earth of Allaah spacious enough for you to emigrate therein?’ Such men will find their abode in Hell — what an evil destination!

98. Except the weak ones among men, women and children who cannot devise a plan, nor are they able to direct their way.

99. These are they whom Allaah is likely to forgive them, and Allaah is Ever Oft-Pardoning, Oft-Forgiving”

[al-Nisa’ 4:97-99]. 

Secondly: 

If he does all that he can but is not able to offer the prayer on time, there is nothing wrong with joining two prayers, so he may join Zuhr and ‘Asr, and Maghrib and ‘Isha’, because of the report narrated by Muslim (705) from Ibn ‘Abbaas (may Allaah be pleased with him) who said: The Messenger of Allaah (peace and blessings of Allaah be upon him) joined Zuhr and ‘Asr, and Maghrib and ‘Isha’, in Madeenah when there was no fear and no rain. According to the hadeeth of Wakee’ he said: I said to Ibn ‘Abbaas: Why did he do that? He said: So that his ummah would not be subjected to hardship, i.e., so that they would not face any difficulty. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked: If a female student enters the classroom at the time when Zuhr begins and the lesson goes on for two hours, what should she do? 

He replied: The time for Zuhr does not end in two hours, because the time for Zuhr lasts from when the sun passes the meridian until the time for ‘Asr begins. This is longer than two hours, so it is possible to pray Zuhr after the lesson ends, because she will still have some time left. This applies if it is not possible for her to pray during the lesson time; if that is possible then it is more on the safe side. If it so happens that the lesson does not end before the time for ‘Asr begins and it will be too difficult for her to leave the lessons, then in that case it is permissible for her to join Zuhr and ‘Asr prayer and delay Zuhr until the time for ‘Asr, because of the hadeeth of Ibn ‘Abbaas (may Allaah be pleased with him) which says that the Prophet (peace and blessings of Allaah be upon him) joined Zuhr and ‘Asr, and Maghrib and ‘Isha’, in Madeenah when there was no fear and no rain.  He was asked about that and he (may Allaah be pleased with him) said: He (peace and blessings of Allaah be upon him) did not want to cause hardship for his ummah.  

These words of Ibn ‘Abbaas (may Allaah be pleased with him) indicate that the hardship and difficulty that a person may face make it permissible for him to join the two prayers which may be joined together at the time of either of them. This comes under the heading of Allaah making religion easy for this ummah, the basis of which is seen in the verses (interpretation of the meaning):  

“Allaah intends for you ease, and He does not want to make things difficult for you”

[al-Baqarah 2:185] 

“Allaah does not want to place you in difficulty”

[al-Maa’idah 5:6] 

“and has not laid upon you in religion any hardship”

[al-Hajj 22:78] 

And the Prophet (peace and blessings of Allaah be upon him) said: ‘Religion is easy”. And there are many other texts which indicate that this religion is easy. 

End quote from Majmoo’ah Fataawa al-Shaykh Ibn ‘Uthaymeen (12/216). 

Thirdly: 

He must offer the prayer in full, not in shortened form, because the one who intends to stay in a place for more than four days comes under the same ruling as a resident according to the majority of fuqaha’. 

There is no connection between joining and shortening prayers. He may join them, as when travelling, or a person may join them when not travelling, because of sickness or istihaadah (non-menstrual vaginal bleeding) or because he fears for himself or his property, or because of heavy rain and other excuses that permit joining prayers, without shortening them, because prayers may only be shortened when travelling.  

And Allaah knows best.