What is eternity?
The Almighty Allah does not demand of His servants what exceeds their strength; rather, only that over which they have power to perform. In fact, the command to promote good and prevent evil is open-ended.
To explain this through an example, the times and rakats for ritual prayer are specified. The days for fasting are limited. Alms come with a threshold amount and a certain ratio. A pilgrimage is fulfilled if done once in a lifetime. Yet, this is not the case for conveying Islam, as well as for promoting good and preventing evil. The command is open-ended. This means that a Muslim must serve the way of Allah (JJ) with every possible means until the final breath.
Anas (RA) explains how, even during his final breath, our Prophet (SAW) felt weighed down by the responsibility of tabligh:
“We were by the side of Allah’s Messenger (SAW) during his final moments on earth. He told us, three times, to:
‘Fear Allah in regards to ritual prayer!’
He then said:
‘Fear Allah in regards to the people under your command and especially over the two weak people: the widow and the orphan. Fear Allah in regards to ritual prayer!’
He then began repeating, ‘Prayer, prayer…’. (Even after his voice could no longer be heard, his lips repeated these words until his spirit ultimately departed). (Bayhaki, Shuab, VII, 477)
We are also able to observe the excitement our Blessed Prophet (SAW) felt for tabligh during his final breath, in his noble companions.
Source: BEING A GUIDING LIGHT, Osman Nuri Topbas, Erkam Publications