فَإِذَا قَضَيْتُمُ الصَّلَاةَ فَاذْكُرُوا اللَّهَ قِيَامًا وَقُعُودًا وَعَلَى جُنُوبِكُمْ فَإِذَا اطْمَأْنَنْتُمْ فَأَقِيمُوا الصَّلَاةَ إِنَّ الصَّلَاةَ كَانَتْ عَلَى الْمُؤْمِنِينَ كِتَابًا مَوْقُوتًا ﴿۱۰۳﴾ وَلَا تَهِنُوا فِي ابْتِغَاءِ الْقَوْمِ إِنْ تَكُونُوا تَأْلَمُونَ فَإِنَّهُمْ يَأْلَمُونَ كَمَا تَأْلَمُونَ وَتَرْجُونَ مِنَ اللَّهِ مَا لَا يَرْجُونَ وَكَانَ اللَّهُ عَلِيمًا حَكِيمًا ﴿۱۰۴﴾ إِنَّا أَنْزَلْنَا إِلَيْكَ الْكِتَابَ بِالْحَقِّ لِتَحْكُمَ بَيْنَ النَّاسِ بِمَا أَرَاكَ اللَّهُ وَلَا تَكُنْ لِلْخَائِنِينَ خَصِيمًا ﴿۱۰۵﴾

﴾103﴿ Fa izaa qadaitumus Salaata fazkurul laaha qiyaamanw wa qu'oodanw wa 'alaa junoobikum; fa izatma'nantum fa aqeemus Salaah; innas Salaata kaanat 'alal mu'mineena kitaabam mawqootaa
﴾104﴿ Wa laa tahinoo fibtighaaa'il qawmi in takoonoo ta'lamoona fa innahum ya'lamoona kamaa ta'lamoona wa tarjoona minal laahi maa laa yarjoon; wa kaanal laahu 'Aleeman Hakeemaa
﴾105﴿ Innaaa anzalnaaa ilaikal Kitaaba bilhaqqi litahkuma bainan naasi bimaaa araakal laah; wa laa takul lilkhaaa'ineena khaseemaa

﴾103﴿ So when you have finished the prayer, remember Allah while standing, sitting, and lying on your sides. Then when you are secure, establish the prayer. Surely, prayer is an obligation upon the believers at its appointed time.
﴾104﴿ And do not weaken in pursuing the people (the disbelievers for battle) because of prayer. If you are suffering, they are also suffering just as you are suffering, but you hope from Allah what they do not hope for. And Allah is All-Knowing, All-Wise.
﴾105﴿ Surely, We have sent down to you the Book in truth so that you may judge between people by what Allah has taught you, and do not be a supporter of the betrayers.

[103] One lesson from this verse is that when you finish the prayer, you should never neglect the remembrance of Allah in any situation, and the meaning of "after completion" is after finishing the prayer. The second point is that when you pray during times of fear, you may perform it separately: some standing, some sitting, and some lying on their sides, and here "after completion" means performing it at times of great fear. This verse also makes it clear that knowing the prayer times is obligatory, and each prayer has its own prescribed time established by authentic hadith. During travel, combining two prayers (Dhuhr and Asr) is confirmed by authentic hadith, as is (Maghrib and Isha), and this does not contradict anything.
[104] This is encouragement for fighting in the way of Allah, not to become weak in jihad because of prayer. (If you suffer) is encouragement to continue fighting despite wounds and pain, because with patience through hardship, you become deserving of reward.
[105] This is the eighth ruling, which is to judge according to the Book of Allah and the sunnah of the Messenger of Allah (May Allah bless him and give him peace), and not to support or defend the criminals. The address is to the Messenger of Allah (May Allah bless him and give him peace), but the ruling applies to all Muslims. (By what Allah has shown you) is a reference to the sunnah of the Messenger (May Allah bless him and give him peace).