I was just reading that the Oslo agreements didn’t include a ban on settlements:

Netanyahu continued construction within existing Israeli settlements, and put forward plans for the construction of a new neighborhood, Har Homa, in East Jerusalem. However, he fell far short of the Shamir government’s 1991–92 level and refrained from building new settlements, although the Oslo agreements stipulated no such ban.
https://en.wikipedia.org/wiki/Oslo_Accords

Perhaps you’re thinking of the Wye River Memorandum?

On 18 December 1998, the Clinton administration and the EU declared their contentment about the implementation of the first phase of the Memorandum by both sides. Israel, however, had only implemented stage 1 of the further redeployment (F.R.D.), meaning that it had withdrawn from 2% of Area C instead of the required 13%. Both parties accused each other of not fulfilling its share of responsibilities under the Wye River Memorandum, and the further implementation of the agreement remained unfinished.

Each side blames the other for it falling apart.