take something with a grain of salt
US /teɪk ˈsʌmθɪŋ wɪð ə ɡreɪn əv sɔlt/
UK /teɪk ˈsʌmθɪŋ wɪð ə ɡreɪn əv sɔlt/

1.
tomar con pinzas, no creer del todo
to not completely believe something that you are told because you think it is unlikely to be true
:
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You should take everything he says with a grain of salt; he tends to exaggerate.
Deberías tomar todo lo que dice con pinzas; tiende a exagerar.
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I'd take that rumor with a grain of salt; it sounds too good to be true.
Yo tomaría ese rumor con pinzas; suena demasiado bueno para ser verdad.