Work done abroad is not Indian income
Start with the reassuring part. Indian tax on salary follows where you actually do the work. Salary is Indian-source only for services rendered in India, under the source rule in Section 9, so salary you earn for work performed entirely abroad is not Indian-source and does not accrue in India. That much is settled, and it is why an NRI working in Dubai or sailing on a foreign ship is not taxed in India on that salary as a matter of source.
The complication comes from a different rule. Section 5 taxes a non-resident not only on Indian-source income but also on income received in India. So even though your salary is not Indian-source, a question arises: by having it paid into an Indian bank account, have you received it in India? That single question is what decides whether crediting your foreign salary to India is safe or risky, and the answer turns on which account it goes to.
The account decides it: NRE safe, resident risky
The key idea is that received in India means first received in India. If the salary is first received abroad, or, on the accepted position, credited into an NRE account, it is treated as a mere remittance of money you already earned and received outside India, and it is not received in India for tax. This is the position built up in the seafarer cases, notably CIT v. Avtar Singh Wadhwan, and confirmed by a CBDT circular for non-resident seafarers whose salary for work on a foreign ship is credited directly to an NRE account, treating it as a remittance and not taxable.
The risk is the resident account. If your foreign employer credits the salary as its very first landing directly into an ordinary resident savings account in India, the department can argue that the first receipt happened in India, and try to tax it under the received-in-India rule. That position is contestable and has been litigated, so it is not a place you want to be. The safe course is straightforward: have your foreign salary paid to a foreign account or to an NRE account, from which you can freely move it, and keep it out of a resident savings account as the first destination. The received-in-India doctrine is built on case law and circulars rather than the bare words of the section, so getting the mechanics right matters. A practising CA sets up the salary flow so your foreign earnings stay clearly outside Indian tax.