poklonjenom konju se ne gleda u zube angolul

don't look a gift horse in the mouth▼(a phrase referring to unappreciatively questioning of a gift or handout too closely)
phrase
[UK: dəʊnt lʊk ə ɡɪft hɔːs ɪn ðə maʊθ] [US: ˈdoʊnt ˈlʊk ə ˈɡɪft ˈhɔːrs ɪn ðə ˈmaʊθ]