The Best and Greatest Word you can utter

Hurayrah (R.A.A.) said that the Prophet PBUH said, "increase recitation of the testimony: 'La ilaha illa Allah' (no God but Allah) before it is intervened between you and it (the witness)'
Classed as Sahih bu Alalbani

The Best and Greatest Word you can utter .

4th Kalma (Tawheed) The word of Oneness

(There is) none worthy of worship except Allah. He is only One. (There is) no partners for Him. For Him (is) the Kingdom. And for Him (is) the Praise. He gives life and accuses death. And He (is) Alive. He will not die, never, ever. Possessor of Majesty and Reverence. In His hand (is) the goodness. And He (is) the goodness. And He (is) on everything powerful.

3rd KALMA (Tamjeed )The word of Glorification

 Glory be to Allah and Praise to Allah, and there is no God But Allah, and Allah is the Greatest. And there is no Might or Power except with Allah.

2nd Kalma (Shahaadat - bearing witness) The word of Testimony

I bear witness that no-one is worthy of worship but Allah, the One alone, without partner, and I bear witness that Muhammad (PBUH) is His servant and Messenger.

1st KALMA (Tayyabah) The word of Purity

"(There is) none worthy of worship except Allah. Muhammad (sal-allahu-alayhi-waallyhi-wsalum) is Messenger of ALLAH."