What are some quotes by the women of Sealand that teach David tolerance?

Almost everyone in Sealand is telepathic, and they feel sorry for people who aren’t but do not discriminate against them.

David and his friends are telepathic.  This means that they communicate with each other through their minds, using what they call "think-pictures."  It also means that they are considered deviants and abominations by their society.  David’s own father considers him as such, and his uncle is already living in the Fringes.  David runs away, along with his girlfriend Rosalind and the other telepaths who have survived.

The telepaths begin to get communications from a Sealanders.  They do not know what the messages are trying to tell that at first.  They get visions of an “L” for Labrador, an “S” and a “Z.”   They learn that Sealand is very far away, because it is not night there.  They also learn that Sealanders are much more tolerant.

'Sealand must be a funny place. Everybody there can make think-pictures — well, nearly everybody — and nobody wants to hurt anybody for doing it.' (Ch. 13)

The Sealanders do not target people just for being telepathic.  Not only that, their way of communicating is not uncommon.  David and the others realize that they have found kindred spirits.

The Sealanders tell Petra that in their country, making “think-pictures” is actually a prized skill, and everyone wants to be able to do it.  According to the Sealand woman, “people who can only talk with words have something missing.”  She tells them to feel sorry for the people who are not telepathic.  This is a very different point of view from the harsh treatment they are used to. 

It seems that the Sealanders possess empathy.  The Sealand woman tries to teach it to them through think-pictures.

' I can't say I feel very sorry for them at present,' I remarked.

'Well, she says we ought to because they have to live very dull, stupid lives compared with think-picture people,' Petra said, somewhat sententiously. (Ch. 13)

The Sealanders clearly disapprove of David’s community’s True Image and the tyrannical imposition of religious dogma.  With them, the telepaths will be welcomed with open arms and treated well.  They will never be persecuted for being different.

Although life has been very hard for the telepaths, the conversation with the Sealand women is the light at the end of the tunnel.  It shows them that they can be valued, and that they will not have to live in fear anymore--at least as long as they can get free of their own people.