def closestNumbers(arr):
    sorted_arr = sorted(arr)
    diff = []
    for i in range(len(sorted_arr) - 1):
        diff.append(sorted_arr[i+1] - sorted_arr[i])
    value = min(diff)
    result = []
    for i in range(len(sorted_arr) - 1):
        if (sorted_arr[i+1] - sorted_arr[i]) == value:
            result.append(sorted_arr[i])
            result.append(sorted_arr[i+1])
    return result