言う

1. Origins, structure, and basic meaning

• Structure: 言う (いう) is a godan verb that reports quoted content and serves as the predicate after a quotation.
• Basic usage: 分からないと言った quotes the speaker’s own assessment, while in 大切だと言った部分 the reporting clause as a whole modifies 部分.

2. Common pitfalls and similar expressions

• Quotation scope before a following noun
  • The clause through 大切だと言った attaches to the following 部分 as a relative clause, so it should not be cut off as an independent past report.