using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<string> lst = new List<string>{"123", "Teste 123 Teste", "ABC", "ABCDE123", "1 2 3" };

        var filter = lst.Where(s => s.Contains("123") || s.Contains("ABC")).Take(3).ToList();

        foreach (var item in filter)

        {

            Console.WriteLine(item);

        }

    }

}