Bisection[a0_, b0_, function_, itt_] :=
 Module[{},
  a = N[a0];
  b = N[b0];
  m = (a+b)/2;

  If[function[m] > 0,
   a = m,
   b = m
   ];

  If[itt  < 0,
   Return[m],
   Return[Bisection[a, b, function, itt--]]
   ];
  ]

f[x_] := x^3 - 5 x + 1;
Bisection[0, 1, f, 7]