Wearing blue cloth & doing karma will not give any benefit - Apastambar

This verse occurs in multiple smritis and in Bhavishya Purana.

स्नानं दानं तपोहोमः स्वाध्यायः पितृतर्पणम्‌ ।
पञ्चयज्ञा वृथा तस्य नीलीवस्त्रस्य धारणात्‌ ॥

Angirasasmriti 1.16

https://archive.org/details/smriti-sandarbha-gurumandal-series/Smriti%20Sandarbha%20Part%201%20-%20Gurumandal%20Series%201952/page/n699/mode/1up

Apastambasmriti 6.3

https://archive.org/details/smriti-sandarbha-gurumandal-series/Smriti%20Sandarbha%20Part%203%20-%20Gurumandal%20Series%201952/page/n235/mode/1up

Bhavishya Purana 1.65.11 (Here the verse occurs with minor variations.

https://sa.wikisource.org/s/jm9

regards
shankara