The defender spent last season on loan to Tottenham Hotspur, and while he had a decent spell, the English club was not willing to pay what the Catalans demanded.
Barcelona are risking being stuck with Lenglet and his massive contract if they did not agree to sell him cheaply. He was not registered by Barcelona and was not making appearances even in preseason.
The Saudi offer then, could be a big relief if it means Barcelona are able to sell the player for a reasonable price.
He will join other players who have made the move from Europe to Al Nassr including Cristiano Ronaldo, Sadio Mané, Alex Telles and Seko Fofana.