Is it
لا إله إلا الله محمدا رسول الله
which translates into
There is no god but Allah and Muhammad is his messenger
?
Or is it
أشهد أن لا إله إلا الله محمدا رسول الله
which translates into
I bear witness that there is no god but Allah and Muhammad is his messenger
?
Are these two formally inter-changeable? Which one is said to enter Islam? Can both be used?