Assalamualaikum ustaz. After the imam completes the Fatihah recitation, should he pause before reciting the surah after that? So that it will give the makmum time to recite the Fatihah?
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
Reciting al-Fatihah is one of the qauli requisites. The prayer is invalid if one didn’t recite the Fatihah. This is based on the statement of the Prophet PBUH:
لاَ صَلاَةَ لِمَنْ لَمْ يَقْرَأْ فِيهَا بِفَاتِحَةِ الْكِتَابِ
“The prayer is not valid I one does not recite Fatihat al-kitab,” 
In explaining this hadith, Imam al-Nawawi: “Reciting al-Fatihah for those who are capable to recite it is an obligation and requisite of which it cannot be translated into any language other than Arabic and it can’t be replaced with any other recitation from al-Quran. It is also obligatory to be recited in all prayers whether it is for obligatory or sunnah prayer.” 
This means that prayer is invalid if al-Fatihah isn’t recited in prayer. If a person forgets to recite al-Fatihah, then the obligation is abrogated from him. This opinion is agreed and concluded by jumhur of scholars in madhhab Syafie. This is stated by Imam al-Nawawi. 
Regarding the issue of the ruling of reciting al-Fatihah for a makmum, we are inclined towards the opinion that it is obligatory for the makmum to recite al-Fatihah in prayer. The al-Fatihah recitation of the imam isn’t sufficient. This is based on a hadith narrated by ‘Ubadah bin al-Samit where Rasullullah PBUH said:
لاَ صَلاَةَ لِمَنْ لَمْ يَقْرَأْ بِفَاتِحَةِ الْكِتَابِ
“He who does not recite Fatihah al-Kitab is not credited with having observed prayer.” 
According to the knowledge of fiqh, the word لاَ in the above hadith is la al-naafiyah which shows the rejection. In the above context, it rejects the validity of a prayer of a person who doesn’t recite surah al-Fatihah.
While the word مَنْ is among the phrase which has a general meaning. This means, the obligation of reciting al-Fatihah a general meaning which covers everyone who prays whether it is an imam or a makmum.
This is the reason Imam al-Nawawi said: “In our madhhab, in our opinion, the makmum is obligated to recite al-Fatihah in every rakaat whether it is al-sirriyah prayer (a prayer where the recitation is recited in a low voice) or al-jahriyyah prayer (its recitation is recited loudly) and this is the sahih opinion that has been previously stated and this is also the opinion of the majority of scholars.” 
He also stated: “The jumhur of the Muslim ummah are of the opinion that it is obligatory to recite al-Fatihah behind the imam whether in sir (low) or jahr (loud).” 
The Makmum Should Recite al-Fatihah at the Same Time the Imam Is Reciting or Listen to the Recitation?
In this issue, jurists have differing opinions regarding the ruling. However, it can be seen in the apparent meaning of the verse in the Quran, Allah SWT states:
وَإِذَا قُرِئَ الْقُرْآنُ فَاسْتَمِعُوا لَهُ وَأَنصِتُوا لَعَلَّكُمْ تُرْحَمُونَ
“So, when the Qur’an is recited, then listen to it and pay attention that you may receive mercy.” 
In the above verse, there is a commandment to listen to the recitation of al-Quran carefully when the verses of al-Quran are recited to us.
The Imam Pauses After the Recitation of al-Fatihah
Coming back to the question presented, we share the opinion of Imam al-Nawawi on this issue. He said: “The sahih opinion states that it is sunnah for an imam in this situation (after the recitation of al-Fatihah) to busy himself with dhikr and supplication. Or he recited the verses of al-Quran in a low voice, for this is the place.” 
This opinion is with the opinion to give time for the makmum behind the imam to complete their Fatihah recitation.
Imam al-Nawawi when stating that it is sunnah to recite dhikr or verses of the Quran in a low voice argued saying: “Pausing doesn’t reject any recitation. This is the same as after the takbiratul ihram we are sunnah to recite the istiftah supplication.”
Imam al-Nawawi commented: It is named as sukut (staying quiet) although there is recitation at the time. Then, he shared a hadith narrated by Abu Hurairah RA, where Rasullullah PBUH was asked:
مَا تَقُولُ فِي سُكُوتِكَ بَيْنَ التَّكْبِيرِ وَالْقِرَاءَةِ قَالَ أَقُولُ اللَّهُمَّ بَاعِدْ بَيْنِي وَبَيْنَ خَطَايَاىَ كَمَا بَاعَدْتَ بَيْنَ الْمَشْرِقِ وَالْمَغْرِبِ اللَّهُمَّ نَقِّنِي مِنْ خَطَايَاىَ كَمَا يُنَقَّى الثَّوْبُ الأَبْيَضُ مِنَ الدَّنَسِ اللَّهُمَّ اغْسِلْنِي مِنْ خَطَايَاىَ بِالثَّلْجِ وَالْمَاءِ وَالْبَرَدِ
“What do you say when you pause briefly between the takbir and recitation?’ He said: ‘I say: O Allah, put a great distance between me and my sins, as great as the distance You have made between the East and the West; O Allah, cleanse me of my sins as a white garment is cleansed from filth; O Allah, wash away my sins with water and snow and hail.'” 
This shows that Imam al-Nawawi used this dalil when analogically deducing it with the above issue. Thus, he said it is sunnah for the imam to pause after reciting al-Fatihah so that the makmum has the time to complete their al-Fatihah. Whilst he pauses, the imam should use the time and fill it with dhikr, supplication or Quranic recitation in a low voice.
To conclude, we state that an imam can continue his Quranic recitation after al-Fatihah if the Quranic recitation is long.
However, if the imam wants to recite short surah after al-Fatihah, it is sunnah to pause a while after the Fatihah to give ample time for the makmum to complete their Fatihah recitation.