What are the famous shlokas in scriptures for glorifying our parents?
उपाध्यायान् दशाचार्य आचार्याणां शतं पिता ।
सहस्रं तु पितॄन् माता गौरवेणातिरिच्यते ॥ १४५ ॥
upādhyāyān daśācārya ācāryāṇāṃ śataṃ pitā |
sahasraṃ tu pitṝn mātā gauraveṇātiricyate || 145 ||
In veneration, the Preceptor excels ten Sub-teachers; the Father a hundred preceptors, and the Mother a thousand Fathers. — (145)
03,297.040 yakṣa uvāca
03,297.040a kiṃ svid gurutaraṃ bhūmeḥ kiṃ svid uccataraṃ ca khāt
03,297.040c kiṃ svic chīghrataraṃ vāyoḥ kiṃ svid bahutaraṃ nṛṇām
The Yaksha asked, 'What is weightier than the earth itself? What is higher than the heavens?' What is fleeter than the wind? And what is more numerous than grass?'
03,297.041 yudhiṣṭhira uvāca
03,297.041a mātā gurutarā bhūmeḥ pitā uccataraś ca khāt
03,297.041c manaḥ śīghrataraṃ vāyoś cintā bahutarī nṛṇām
Yudhishthira answered, 'The mother is weightier than the earth; the father is higher than the heaven; the mind is fleeter than the wind; and our thoughts are more numerous than grass.'
Circumambulating one's parents give virtues equivalent to that of circumambulating the whole earth.
जननी जन्म भूमिश्च स्वर्गादपि गरीयसी || 6.124.17
Mother and mother-land are far superior to even the heaven.
Note: Few scholars say that this shloka is not in all versions of Valmiki Ramayana.
Ayodhya Kanda of Valmiki Ramayana; Lord Rama to his father:
पिता हि दैवतम् तात देवतानामपि स्मृतम् | २-३४-५२
Oh, father! It was indeed said that even for celestials, father is the god.
The mother is weightier than the earth; the father is higher than the heaven.
Ayodhya Kanda of Valmiki Ramayana; Lord Rama to his wife:
यत्त्रयं तत्त्रयो लोकाः पवित्रं तत्समं भुवि।
नान्यदस्ति शुभापाङ्गे तेनेदमभिराध्यते।।2.30.34।।
न सत्यं दानमानौ वा न यज्ञाश्चाप्तदक्षिणाः।
तथा बलकरा स्सीते यथा सेवा पितुर्हिता।।2.30.35।।
स्वर्गो धनं वा धान्यं वा विद्याः पुत्रास्सुखानि च।
गुरुवृत्त्यनुरोधेन न किञ्चिदपि दुर्लभम्।।2.30.36।।
प्राप्नुवन्ति महात्मानो मातापितृपरायणाः।।2.30.37।।
Where these three(mother,father and preceptor) equal to the three worlds are, O one with loverly sideglances, there is none in this world as holy. Therefore, they are to be worshipped.
Truth or munificence or homage or distribution of gifts to the revered ones or sacrifices, O Sita, are not considered as efficacious as service to father.
By fulfilling father's wish, nothing is difficult to achieve, whether it is heaven, or wealth, or foodgrains, or learning, or sons or other comforts.
Great men who are devoted to the service of their parents attain the world of the gods, of gandharvas, of cows, of Visnu, of Brahma and other worlds.
There are many shlokas in our scriptures which glorify parents. I am giving some of them.
From Taittiriya Upanishad Shikshavalli eleventh Anuvaka,
मातृदेवो भव । पितृदेवो भव । आचार्यदेवो भव । अतिथिदेवो भव ॥ ४ ॥
- Treat thy mother as a God; as a God treat thou thy father; as a God shalt thou treat thy teacher; thy guests as Gods shalt thou treat.
Ramayana is a celebration of Pitru vaakya paripaalana (following father's words). There are a bunch of shlokas in the Ayodhya Kanda which talk about parents importance.
There are a lot of verses from Puranas which say the significance of parents. In fact, every Purana has verses (total chapters) which are dedicated to glorify the importance of parents.
For example, From Padma Purana Srishti Kanda Chapter 50
O brahmanas, that righteousness (i.e. religious merit) which a man would earn by adoration of his parents cannot be earned even by performing hundreds of sacrifices or by going on pilgrimages to sacred places on the earth.
A father (a mother) is righteousness, a father (a mother) is heaven, a father (a mother) is a great penance; when the father is pleased, all deities are pleased.
He whose parents are pleased by his service to them and his virtue, has bathed in the Ganges everyday.
11-12a. A mother is full of (i.e. has the merit of) all sacred places; a father is full of gods (i.e. has all gods unite in him). He who goes round his mother and father keeping them to his right, has (indeed) gone round the earth with the seven islands.
12b-13a. He whose knees, hands and head, when saluting the parents, touch the ground, obtains (i.e. lives in) heaven eternally.
13b-14a. As long as the marks of the dust of their feet have clung to his head (and other) parts (of the body) their son is purified.
15b-16a. He is blessed in the human world, he is purified from all sins. (Such) a man obtains the status of Vinayaka in (i.e. after) one existence only.
From Manu Smṛti:
Ācāryaśca pitā caiva mātā bhrātā ca pūrvajaḥ |
nārtenāpyavamantavyā brāhmaṇena viśeṣataḥ || 225 ||
The preceptor, the father, the mother and the elder brother should not be treated with disrespect, especially by a Brāhmaṇa,—even though he be distressed.
Ācāryo brahmaṇo mūrtiḥ pitā mūrtiḥ prajāpateḥ |
mātā pṛthivyā mūrtistu bhrātā svo mūrtirātmanaḥ || 226 ||
The preceptor is the embodiment of Brahman; the father is the embodiment of Prajāpati; the Mother is the embodiment of the earth, and one’s own brother is the embodiment of the self.
yaṃ mātāpitarau kleśaṃ sahete sambhave nṛṇām |
na tasya niṣkṛtiḥ śakyā kartuṃ varṣaśatairapi || 227 ||
The trouble that the parents undergo in the birth of children,—for that there can be no compensation even in a hundred years.
Viṣṇu Smṛti says the same.
For man there are three super-elders;— the Father, the Mother and the Ācārya;—one should ever attend upon these;— one should do what is agreeable and beneficial to these. (31.1)