President Trump hasn’t said the words “I pressured Ukrainian president Volodymyr Zelensky into investigating Joe Biden.” So if that’s what you’re looking for, you aren’t going to find it. What I’m guessing people are talking about are statements in which the president implicitly admits to asking for compromising information about Joe Biden. This matters because it is illegal under US federal law to ask any citizen or government of a foreign nation for help winning an election. With that in mind, here are two statements that have been interpreted as Trump admitting to that crime.
Starting at about thirty seconds into this video from September 20th, Trump says the following:
“The conversation I had was largely congratulatory. It was largely corruption—all of the corruption taking place. It was largely the fact that we don’t want our people, like Vice President Biden and his son, creating to [sic] the corruption already in the Ukraine.”
On September 24th, Trump also said the following at the United Nations in response to a question about what he told the Ukrainian president about Joe Biden:
“It’s very important to talk about corruption. If you don’t talk about corruption, why would you give money to a country that you think is corrupt?”
Trump’s answer does not mention Biden by name since he had already been mentioned in the question itself, but it is another implicit admission that he discussed Biden in connection with the issue of corruption when he spoke to Zelensky.
The first 30 seconds of this video from September 19th also show Rudy Giuliani, Trump’s personal lawyer, first denying and then admitting to asking Ukraine to investigate Joe Biden.
Here is how the interview opens:
Cuomo: Did you ask Ukraine to investigate Joe Biden?
Giuliani: No, actually I didn’t.
Then, seconds later, this exchange happens:
Cuomo: So you did ask Ukraine to look into Joe Biden.
Giuliani: Of course I did!
Giuliani is not Trump, but he is nevertheless relevant since the president indicated that Giuliani is one of the people tasked with following up on the topics discussed with Zelensky. This is despite the fact that Giuliani is Trump's personal lawyer and not an official member of either the administration or the US federal government.
One last thing: the memo released by the White House is not a verbatim transcript of Trump’s conversation with Zelensky. It is a reconstruction of what was said based on a number of sources. The document itself even says so:
“CAUTION: A Memorandum of a Telephone Conversation (TELCON) is not a verbatim transcript of a discussion. The text in this document records the notes and recollections of Situation Room Duty Officers and NSC policy staff assigned to listen and memorialize the conversation in written form as the conversation takes place. A number of factors can affect the accuracy of the record, including poor telecommunications connections and variations in accent and/or interpretation.”