initiation into holy mantras
In the standard texts a very rigorous practice is prescribed for a disciple to get initiated into a mahamantra.. Serving the Guru for long periods, worship of certain deities, physical and mental exercises like Pranayama, frequent baths and many other very tough practices are prescribed..
But in a text Updeshasudhaatantram the following rule is mentioned
चन्द्रसूर्यग्रहे चैव सिद्धक्षेत्रे शिवालये
मन्त्रमात्रप्रकथनमुपदेशः स उच्यते॥
candrasūryagrahe caiva siddhakṣetre śivālaye
mantramātraprakathanamupadeśaḥ sa ucyate||
During the periods of eclipses of the Moon or the Sun
While stationed at the Lands of Gods and Sidhas.. like Himalyas, and some holy lands like Badari ete
While worshipping the Lord in the Temple of Lord Siva
Even a chance hearing of a holy name of the divinity or a mantra is considered as having gained initiation into that mantra..
Views can differ on this, but the sacredness of the muhurtams mentioned are never in doubt..
( It may be noted that there are Shiva temples where pooja and dhaara are performed during the eclipses.. although most of the temples are supposed to be closed during that period)