Work of Dawah done by Prophet (PBUH) and Sahaba Karam was having steadfastness on deen and two basic tools.
1. Migration & Motion and
2. 'Collectiveness' are the soul and the foundation principles of this Ummat.
In the 1st century Hijrat, Deen got spread all over the world.
We should all think over this fact that the resources - both material and spiritual - which we consider as necessary for spreading deen today, were not present in the days of Sahaba (radiyallahu anhum).
The spiritual means of which we have today, for example, printed copies of the Holy Qu'ran and Hadiths,
Qur'an was printed centuries later.
Imam Bukhari rahmatullah Alaihi, who is the first in the line of and is the leader of the Commentators of Hadiths, born in 194H, that is, after about two centuries of the start of Islam, and worked on Hadiths at least two decades later.
Only that thing spreads which remains in motion. The sun remains in motion. It spreads light. One perfumed handkerchief, if moved in a gathering, spreads sweet smell in the entire room.
A street-hawker moves with oranges, and oranges get spread in all the locality. Sah'aba (radiyallahu anhum) migrated and moved with iman and worships.
They traveled all the time, both on land and in the water:
They are travelling and reciting Qur'an; traveling and offering salat; traveling and doing zikr - hence, Qur'an spread, salat spread, zikr spread.
The Holy Prophet (sallallahu a'laihe wasallam) put all the Ummat to migration and motion:
See the lives of the Sahaba (radiyallahu anhum):
1. A'mr Bin Jamooh (r.a): he was lame by birth, and got martyrdom in the battle of Uhud with his keen desire.
2. Their old are in motion: Abu Ayub Ansari (r.a); he died at the age of 95 while in the sea-travel of the Jihad of Turkey.
3. Their children are in motion: Ma'az and Mu'waz (r.a); they killed Abu Jahl in the battle of Badr.
4. Their newly-married are in motion: Hanzalah (r.a); he had just left the bed of his wife and was about to take bath when he heard the news of defeat in Uhud, thus with sword in hand he rushed the battle-field and fought till dealth.
5. Their women are in motion: Safiyaah (r.anha); she killed a spying Jew with giving a blow of a tent-peg on his head.
6. Their rich are in motion: Abdul Rhaman Bin A'uf (r.a); he was the richest of all the Muslims.
7. Their poor are in motion: Mus'ab Bin Umair (r.a); he was brought up in luxury and comfort but did not have sufficient cloth even to cover his dead body.
In short, all the Ummat was in the state of migration and motion...
So much motion made the Sahaba ra for Deen - so much that they were born at some place, worked for Deen at some other place, and their graves are at some different place.
A. Hazrat Bilal (radiyallahu anhum) - born in Abyssinia, suffered hardships for Deen in Makkah and made and made efforts for Deen in Madinah, and died in Damascus (Syria).
B. Abu Ayub Ansari (r.a) - born in Madinah, traveled long way for Deen by sea, and his grave is in Constantinople (Turkey).
C. Graves of 10 sons of Hazrat Abbas (r.a) are in 10 different countries.
In those days, there was a common atmosphere of migration and motion. This is the time when, with courage, all the Ummat should be made to put to migration and motion.
Secondly, in collectiveness (unity)
If these two things and this style of working (methodology) regains life, Deen will spread before our eyes. As Allah had made the sun the means of emerging heat. So has he made the effort of the Holy Prophet (sallallahu a'laihe wasallam) the mean of spreading Deen in the entire world.
When the ummah moved Deen spread , when the ummah stoped moving Deen came to a stop.