Seems like you and me have different set of letters. Since I don't know the content of your approval letter, here is content of my passport request letter
This is in reference to your application for temporary residence. A decision has been made on your application. We require your passport to finalize processing your application. Passport requirements • Please provide your passport or travel document, with a copy of this letter. • There must be at least one blank page in your passport. • Your passport must be valid for the duration of your expected length of stay in Canada. • Please note that we cannot issue a visa beyond the expiry date on the passport. Your passport must be received by Immigration, Refugees and Citizenship Canada within 30 days from the date of this letter. Failure to do so could result in the refusal of your application. Please ensure that a copy of this letter is included with your passport. To find out where to send your passport, visit our website: Thank you for the interest you have shown in Canada. Attention: The unique client identification (UCI) number in the upper left corner of this letter is your personal identification number. For your own protection, do not allow any person, other than an authorized representative, to use this number as it provides access to personal information on your file. Immigration, Refugees and Citizenship Canada