Not much I'm afraid
.
You can see Lam's name in the title and the photo was taken after his funeral.
Sammo was asked about Lam's illness. Sammo told the journalists that he knew NOTHING about his illness, and got his death notice from the papers. Lam did not tell noone that he is dieing, just a handful of people, who kept his secret.
The dear friend, Sammo was very upset, hurt and even angry at him for facing his illness alone and for not letting his friends to share in his pain. He expressed if he knew earlier, he would have tried his best to help him on his treatment, to introduce doctors to him. Although he couldn't guarantee he would be cured, but anything was worth to try. So he felt Ching Ying was too stubborn, carrying everything by himself.
It turned out that he did not WANT to tell Sammo, because he knew that Sammo is
very strong and would wanted him to see the doctor. Endless, needless treatments, lying all the time, being sick over and over again in need of others' help, chaining somebody to his bed for days and nights he did not want.
So that is why Sammo looked so sad on that photo. He was disappointed a bit in their friendship, I think.