Prayer in congregation is obligatory at all times, because Allaah says (interpretation of the meaning): 

“When you (O Messenger Muhammad) are among them, and lead them in As‑Salaah (the prayer), let one party of them stand up [in Salaah (prayer)] with you taking their arms with them; when they finish their prostrations, let them take their positions in the rear”

[al-Nisa’ 4:102]

Allaah has enjoined prayer in congregation at times of war, so how about at times of peace? 

Al-Bukhaari (608) and Muslim (1040) narrated that the Prophet (peace and blessings of Allaah be upon him) said: “I was thinking of ordering that firewood be gathered, then I would order that the call to prayer be given, then I would order a man to lead the prayer, then I would go to men who do not attend the prayer and I would burn their houses down around them.” In Saheeh Muslim (1044) it says: A blind man came to the Prophet (peace and blessings of Allaah be upon him) and said: “O Messenger of Allaah, I do not have a guide to bring me to the mosque.” He asked the Messenger of Allaah (peace and blessings of Allaah be upon him) to grant him a concession allowing him to pray in his house, and he granted him that concession, but when he turned to leave he said: “Can you hear the call to prayer?” He said: “Yes.” He said: Then answer it.” So the Muslim should regularly pray in congregation at all times, and not let any worldly distractions keep him away from that. 

Allaah says (interpretation of the meaning): 

“O you who believe! Let not your properties or your children divert you from the remembrance of Allaah. And whosoever does that, then they are the losers”

[al-Munaafiqoon 63:9]

You should advise your father and remind him of this saheeh evidence, with wisdom and beautiful preaching. 

This ruling applies to offering the five daily prayers in congregation. With regard to Taraweeh, the matter is easier than that. It is permissible for a Muslim to pray Taraweeh at home, although it is better to pray it in congregation in the mosque. 

It is not permissible for a Muslim to devote himself to worldly work at the expense of his worship and prayer. Allaah has described the believers as those who do not let their trade and selling distract them from the remembrance of Allaah and establishing prayer. Allaah says (interpretation of the meaning): 

“In houses (mosques) which Allaah has ordered to be raised (to be cleaned, and to be honoured), in them His Name is remembered [i.e. Adhaan, Iqaamah, Salaat (prayers), invocations, recitation of the Qur’aan]. Therein glorify Him (Allaah) in the mornings and in the afternoons or the evenings,

37. Men whom neither trade nor sale (business) diverts from the remembrance of Allaah (with heart and tongue) nor from performing As‑Salaat (Iqaamat‑as‑Salaat) nor from giving the Zakaah. They fear a Day when hearts and eyes will be overturned (out of the horror of the torment of the Day of Resurrection).

38. That Allaah may reward them according to the best of their deeds, and add even more for them out of His Grace. And Allaah provides without measure to whom He wills”

[al-Noor 24:36-38]

This passage ends with the words “And Allaah provides without measure to whom He wills”, which hints to the one who spends his time in trade and work at the expense of his obedience to his Lord, that provision is in the hand of Allaah and He provides without measure to whom He wills. The Prophet (peace and blessings of Allaah be upon him) explained that when he said: “O people, fear Allaah and be moderate in seeking a living, for no soul will die until it has received all its provision, even if it is slow in coming. So fear Allaah and be moderate in seeking provision; take that which is permissible and leave that which is forbidden.” Narrated by Ibn Maajah, 2144, from the hadeeth of Jaabir ibn ‘Abd-Allaah (may Allaah be pleased with him); classed as saheeh by Shaykh al-Albaani in Saheeh al-Targheeb (1698). 

There is no reason why you should not do what you can to earn a living, but the Muslim should not go to extremes with work and devote all his time to it at the expense of his worship, health and raising his children. He should create a balance between everything. 

We hope that your father will study what we have said and think about it properly. We ask Allaah to guide him to the best of words, deeds and attitudes, and to bless him with a goodly and blessed provision. 

And Allaah knows best.