I learned from you, group dua after each prayer is not acceptable. Also in our mosque, on every Friday after the speech by the Imam (before the Kutba) he used to make dua for the people who died and hospitalised during the week and for the people who donate money for the students in the Quran Class. Can I join that dua?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is permissible for you to supplicate when being with the congregation after the lectures; Shaykh Ibn Baaz said: “It is permissible to supplicate after a lecture, or admonition, or a reminder; it is permissible to supplicate; one may supplicate to Allaah for the audience for their guidance, for them to be enabled to perform good deeds, and for having a sincere intention [i.e. performing an act of worship only for the Sake of Allaah] and that their deeds be in conformity with the Book of Allaah and the Sunnah of the Prophet ; but raising the hands in such a circumstance is something I do not know any evidence about. I am not aware of anything reported from the Prophet in this regard except general evidence, like raising the hands in supplication in general and that it is among the reasons of having one’s supplication answered, but I have not heard that he used to raise his hands and supplicate when he admonished the people. If he used to do this, most certainly the Companions would have reported this from him, as they did not leave anything about him except that they had reported it to us, so to be on the safe side, it is more appropriate not to raise (the hands) in such a case, except if there is evidence which proves it. However, if the Imaam supplicates for them after he finishes, by saying for example ‘may Allaah forgive us and you’, ‘may Allaah enable us to do good deeds’, and ‘may Allaah make us and you benefit from what we have heard’, and the like, then this is permissible, and if they say 'Aameen' there is no harm in that.”

Also, what is reported by At-Tirmithi may be evidence about the permissibility of supplicating after delivering a speech (lecture); Ibn ‘Umar said: “It was very rare that the Prophet would stand up from a meeting before he had supplicated with these supplications for his Companions: “Allaahumma, iqsim lana min khashyatika ma yahoolu baynana wa bayna ma‘siyatic; wamin taa‘atika ma tuballighuna bihi jannatak; waminal yaqeeni ma tuhawwinu bihi ‘alayna masaa’ibad-dunya. Wa matti‘na, Allaahumma, bi’asmaa‘ina, wa absaarina, wa quwwatina ma ahyaytana, waj’alhul-waaritha minna. Waj‘al tha’rana ‘ala man thalamana; wansurna ‘ala man ‘aadaana. Walaa taj’al museebatana fee deenina; walaa taj‘al ad-dunya akbara hammina wala mablagha ‘ilmina. Wala tussallit ‘alayna man laa yarhamuna.” (O Allaah, apportion to us such fear as should serve as a barrier between us and acts of disobedience; and such obedience as will take us to Your Paradise; and such as will make easy for us to bear the calamities of this world. O Allaah! Allow us to enjoy our hearing, our eyesight and our power as long as You keep us alive and allow this to remain until our death, and make our revenge restricted to those who oppress us, and support us against those who are hostile to us, let no misfortune afflict our religion; let not worldly affairs be our principal concern, or the ultimate limit of our knowledge, and let not those rule over us who do not show mercy to us.)

This above supplication/Hadeeth is not included in what we have mentioned regarding the non-permissibility of congregational supplication after the prayer as the above supplication is not said after the prayer. Indeed, there are some specific supplications/Athkaar (legislated mention of Allaah) which are mentioned after the prayer but there is no congregational supplication in the Sunnah in this regard.

Allaah Knows best.