Las prisas son malas consejeras

[ROBINDESBOIS]

In English?
It means that when we do sth in a hurry, we might make a mistake.

[bobjenkins]

Haste makes waste

Esa traducción es mía:)

[pjt33]

I can think of a couple of sayings which are in the right area but not quite the same:

Marry in haste, repent at leisure
More haste, less speed

[poli]

Easy does it.

[sosia]

Another saying with the same idea
"Visteme despacio que tengo prisa"
Saludos :D

[poli]

Slow and steady wins the race.