Hadith -- Best of both the worlds

Sayyiduna Abu Razin (RadhiAllaho anho) narrates that
Rasul'Allah (SallAllahu Alaihi Wasallam) said:

Should I not guide you
to the fundamentals of Deen
by which you will obtain
the best of this world and the Hereafter?

Make it incumbent upon yourself
to frequent the gatherings of those
who engage in Dhikr.

And when you are alone,
engage your tongue
in the remembrance of Allah
as much as you can.

{Baihaqi, Mishkat}