tried and tested/trusted

tried and tested

Proven to be reliable through frequent, widespread, or long-time use. The tried and tested method for getting someone to confess is to just let them keep talking. The tried and tested first food for babies is rice cereal, but you can really feed them anything mushy.
See also: and, test, tried
Farlex Dictionary of Idioms.

ˌtried and ˈtested/ˈtrusted

(British English) (American English ˌtried and ˈtrue) that you have used or relied on in the past successfully: We’ll be using a tried and tested technique to solve the problem.
See also: and, test, tried, trust
Farlex Partner Idioms Dictionary
See also:
  • tried and tested
  • benefit of the doubt, to give/have the
  • vouch
  • vouch for
  • vouch for (someone or something)
  • in-your-face
  • get (something) off one's chest, to
  • unsusceptible to (something)
  • be too many for
  • be too many for (someone)