How can I validate that a field of the form only allows text ?, that is, do not accept a number or other characters other than normal letters of the alphabet.
I assumed that this would be enough
"campo" => "required|string"
but if I enter the number 1 it allows recording in the database
Why wait to go to the backend to validate it, if you can validate from the input with html5 in the following way:
<input type="text" pattern="^[a-z]{20}" title="solo acepto letras">
[a-z] here you indicate that you only accept letters from a to z in lowercase.
{20} here you indicate that you accept 20 characters.