def closestNumbers(arr):
    arr = sorted(arr)
    lowest = float("inf")
    minimum = []
    for i in range(len(arr) - 1):
        if arr[i + 1] - arr[i] < lowest:
            lowest = arr[i + 1] - arr[i]
            minimum = [arr[i], arr[i + 1]]
        elif arr[i + 1] - arr[i] == lowest:
            minimum.append(arr[i])
            minimum.append(arr[i + 1])
    return minimum