The Promised Mahdi ^AHS had made the 'retreat' (Uzlat - uz - Khalq) compulsory (Farz) on his followers because Allah Tala in the Holy Quran has commanded that . . .

			وَاذْكُرِ اسْمَ رَبِّكَ وَتَبَتَّلْ إِلَيْهِ تَبْتِيلا ۝ 073.008 But keep in remembrance the name of thy Lord and devote thyself to Him whole-heartedly. Al-Qur'an, 073.008 (Al-Muzzammil [The Enshrouded One, Bundled Up])

i.e., be fully attentive towards Allah and get disconnected completely from other than Allah. Though this command of Allah is for the Prophet ^PBUH but according to the sense, the order is general.

Further, it is ordered that . . .

			وَذَرِ الَّذِينَ اتَّخَذُوا دِينَهُمْ لَعِبًا وَلَهْوًا وَغَرَّتْهُمُ الْحَيَاةُ الدُّنْيَا وَذَكِّرْ بِهِ أَنْ تُبْسَلَ نَفْسٌ بِمَا كَسَبَتْ لَيْسَ لَهَا مِنْ دُونِ اللَّهِ وَلِيٌّ وَلا شَفِيعٌ وَإِنْ تَعْدِلْ كُلَّ عَدْلٍ لا يُؤْخَذْ مِنْهَا أُولَئِكَ الَّذِينَ أُبْسِلُوا بِمَا كَسَبُوا لَهُمْ شَرَابٌ مِنْ حَمِيمٍ وَعَذَابٌ أَلِيمٌ بِمَا كَانُوا يَكْفُرُونَ ۝ 006.070 Leave alone those who take their religion to be mere play and amusement, and are deceived by the life of this world. But proclaim (to them) this (truth): that every soul delivers itself to ruin by its own acts: it will find for itself no protector or intercessor except Allah: if it offered every ransom, (or reparation), none will be accepted: such is (the end of) those who deliver themselves to ruin by their own acts: they will have for drink (only) boiling water, and for punishment, one most grievous: for they persisted in rejecting Allah. Al-Qur'an, 006.070 (Al-Anaam [Cattle, Livestock])

i.e., 'O! Mohammed ^PBUH desert those people and be away from them who have treated their Deen a jest (play)'. The order of this verse also according to its sense is in general. It may be noted, that according to the command of Allah, when the Promised Mahdi ^AHS had made renunciation of world (Tark e Duniya) a compulsory tenet, then those who have renounced the world would be craving for the concentration. Hence, Promised Mahdi ^AHS has made the isolation i.e., isolating themselves from other than Allah, a compulsory deed. Because, when a person is involved in other than Allah, then he would be away from Allah and would be involved in self seeking and would become self centered. Such a person in reality would not be a person who has renounced the world. Thus, for a person who renounces the world, isolation (Uzlat uz Khalq) is compulsory when the reason is made compulsory, then the condition also is compulsory. The connection between the Tark e Duniya and Uzlat us Khalq is clear from the very sense of Tark e Duniya, because according to our terminology self-seeking and self (nafs) is the duniya (world), then the meanings of Tark e Duniya would be Tark e Khudi (renunciation of self) and the one who has renounced the self would be close to Allah. Moreover, the one who is close to Allah would be disconnected from the creations. Thus, one who has renounced the world would be disconnected from the creations.

			Note: It is narrated that Bandagi Miyan Shah Nizam RZ asked Imam Mahdi's AHS permission to remain in seclusion. Imam Mahdi AHS said: "One should remain in a place where one could hear someone say something or should say something which others hear."