Why Did Whitebeard Go To God Valley?

The recent flashback in the Elbaf arc in the One Piece Manga seems to drop more into the past generation of pirates, making the things we thought we knew seem like a joke.
In the last manga chapter numbered 1160, we witnessed the landing of Rocks Pirates at the God Valley, and each of those big shots was there with a purpose of their own.
While the world Government thinks they are after Shakky, the truth the top players of the Rocks Pirates each have their own goal.
Xebec, the captain of the Rocks Pirates, is there to save Blackbeard (his son) and his wife. We know that Big Mom, Linlin, is after Devil Fruits, and so is Kaido.
But the one thing that shocked not just fans but also the other Rocks crew was what White Beard told them his purpose was.
Whitebeard, as soon as he lands at God Valley, says that he is there to help his friend. This confession seems surprising not only to us, but even his crewmate seems to be shocked and asks what he is talking about.
Whitebeard is not there to save Rogers; well, he needed no saving, and they weren’t that close back then. Some think it was Shakky, the main prize of the hunt, that he called a friend.
This may come as a shocker because everyone else had some kind of romantic feelings for Shakky, while very few saw her just as a friend and the most notable one is said to be Whitebeard.
But no matter the reason or who the friend was, Edward Newgate did not come to slack, as we know that the battle between him and Figarland Garling was the second most intense fight in the Valley, which even left him with a scar that he could never forget.