If someone teaches knowledge and it is acted upon, he will have a reward like that of everyone who learns it through him and acts upon it, until the Day of Resurrection

It was narrated from Abu Hurayrah that the Messenger of Allah (blessings and peace of Allah be upon him) said: “Whoever calls others to guidance will have a reward like that of those who follow it, without that detracting from their reward in the slightest. And whoever calls others to misguidance will have a burden of sin like that of those who follow it, without it detracting from their burden in the slightest.” Narrated by Muslim (2674).

It was narrated that Abu Mas‘ood al-Ansaari (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “The one who tells another about a good deed is like the one who does it.” Narrated by Muslim (1893).

The Prophet (blessings and peace of Allah be upon him) said: “Whoever sets a good precedent in Islam will have the reward for that and the reward of those who do it after him, without that detracting from their reward in the slightest.” Narrated by Muslim (1017).

And he (blessings and peace of Allah be upon him) said: “When a man dies, all his good deeds come to an end except three: ongoing charity (sadaqah jaariyah), beneficial knowledge, or a righteous son who will pray for him.” Narrated by Muslim (1631).

These hadiths indicate that the one who teaches someone beneficial knowledge will have reward like that of the one who benefits from this knowledge, and that that reward will continue, uninterrupted, for everyone who learns this knowledge through him.

Hence the Messenger of Allah (blessings and peace of Allah be upon him) will have a reward like that of the entire ummah.

Al-Minnaawi (may Allah have mercy on him) said:

All our good and righteous deeds, and the acts of worship of every Muslim, are written in the record of our Prophet (blessings and peace of Allah be upon him), in addition to what he himself has of reward, and he will attain multiple reward, many times the number of his ummah, beyond reckoning, such as the human mind is not able to grasp. For everyone who guides people, shows them the righteous path and teaches them will have reward until the Day of Resurrection. A similar reward will be accredited to his shaykh who guided him, and the shaykh of his shaykh will have twice as much, the third shaykh will have four times as much, the fourth shaykh will have eight times as much, and so on; at every link in the chain, it will be multiplied, all the way back to the Prophet (blessings and peace of Allah be upon him).

So if we assume that there are ten links in the chain of transmission of knowledge after the Prophet (blessings and peace of Allah be upon him), the Prophet (blessings and peace of Allah be upon him) will have one thousand and twenty-four rewards. If an eleventh link follows the tenth, then the reward of the Prophet (blessings and peace of Allah be upon him will be two thousand and forty-eight, and so on. Every time another link is added, the reward of those who came before him will be multiplied, until the Day of Resurrection. This is something that no one can calculate except Allah, so how about if we take into account the great number of the Sahaabah and Taabi‘een, and the Muslims in each era?

For each one of the Sahaabah, as a result of their actions, there will be rewards like those of all the people in the links until the Day of Resurrection. All the reward attained by the Sahaabah will also be accredited to the Prophet (blessings and peace of Allah be upon him). Thus it becomes clear that the early generations (salaf) are superior to the later generations (khalaf), and that the more the later generations earn of reward, the more the reward of the early generations will increase and multiply. Whoever reflects on this meaning and is helped and guided by Allah will be motivated to teach others and spread knowledge, so that his reward will be multiplied during his life and after his death, without ceasing, and he will refrain from introducing innovations (bid‘ah) and wronging others by collecting unjust levies (mukoos) and otherwise, for this will multiply his sins and bad deeds in the manner described, so long as there is anyone who is still doing that. So let the Muslim reflect on this meaning, and think of how blessed the one who promotes the path of good will be and how wretched the one who promotes the path of evil will be." (Fayd al-Qadeer  6/170).

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:

There will be written for the Prophet (blessings and of Allah be upon him) the reward of everything that the ummah does. For everything that we do of good and righteous deeds, both obligatory and supererogatory, the rewards thereof will also be recorded for the Messenger (blessings and peace of Allah be upon him), because he is the one who taught us." (Sharh Riyaadh as-Saaliheen  2/258).

So if you teach someone any adhkaar, you will have a reward like that of everyone who learns these adhkaar from the one whom you taught, until the Day of Resurrection.

And Allah knows best.